How important is physical touch?

You're so welcome! In our flocks, we do basically do small health checks daily, this would be just looking over their eyes, toes, combs/wattles. Our gents have moved inside with us now (just getting enrichment time outside at this point) so we wind up inspecting vents twice daily at diaper change time, but prior to that I'd say I checked them every few days. This time of year, I like to do more frequent vent checks because of the danger of fly strike (if you aren't familiar with it, be cautious looking up any photos, it's quite horrifying). The gist of it is that flies can be drawn to poop collected against the skin near the vent (or any open wounds, even those that might not yet have been identified), injury or contact with droppings makes the skin weak and sensitive, and those flies will be attracted to lay eggs in that area. These then hatch into maggots that feed on the damaged living tissue. Any time there's significant fly presence, I'm checking butts like it's my second job. This could likely be done on the roost at night as well if needed, if it's something you think could be a risk in your area.

As for full checks (ears, bottoms of feet, under wings and at feather bases for signs of mites/lice, etc) I would think weekly would be ideal. The main thing is to think of the time it takes to remedy the specific issues you're checking for, if worst case you do find signs of any. For instance, if someone has a small cut festering on their foot pad, how long will it take for that to become full blown bumble foot. If a respiratory infection is brewing, how long could that continue before they're in a terrible place. You want the time between checks not to exceed that length of time. Remember, chickens are stoic and are known to hide symptoms of illness until things are very progressed. Early detection really is the key to effective treatment for many ailments. Even though something like bumble or RI would eventually be noticed through things like limping, wheezing, lethargy, etc. the odds are good that by that point it will be a very uphill battle getting it under control, and it may not even be possible anymore by that point. So what we're aiming to do is confirm no "hidden" symptoms or maladies are present frequently enough that we'd catch signs while they're still very early, and have time to treat before it gets out of control. Checking droppings regularly, at least daily, is fantastic as well as it can give you sort of a guide to their normal patterns, and therefore alert you if anything suddenly changes. Just take note of who's roosting where at night when you go to lock up, then look under the roost once they're out for the day to confirm all looks normal and nobody has any signs of potential issues. Do note, chicken droppings naturally vary in size, color, and consistency depending on what they've eaten and their water consumption. A change isn't a definite sign of a problem, just something to watch and maybe look into further, especially if you can't see a good explanation for the change. Runny droppings on a very hot day make sense, increased water intake. Runny droppings in winter would be a much greater cause for concern. If you need to start with less frequent checks it's still far better than none, but just keep in mind however long you wait between them will determine how long a potential problem would have to develop and worsen.

It can definitely be overwhelming reading all the health related horror stories, but remember, you only see the stories of the people who are running into issues. The keepers (and there are a great many) who are having no problems have no reason to get online and seek help. It's like bad reviews, customers who have no complaints often don't say anything so the feedback winds up warped. Also, as the old adage goes, an ounce of prevention is worth a pound of cure and so many of these things can be prevented or be easily remedied just by keeping a good close eye on the flock, learning their norm, and not dismissing any sudden or unexpected changes to it. I once recognized that one of our girls had a problem simply because she spent maybe an extra minute on the coop patio when the other ladies were busy getting up on the roost. She had no visible problem, looked completely normal, but she seemed to be stalling. It was unlike her to be reluctant to get settled in, so we brought her inside, looked her over more closely, and noticed her vent was pulsing with some clear discharge. Best guess was egg binding based on that presentation, so we put her in a warm soak. Sure enough, maybe 15 minutes later she laid a soft shell egg in my lap that she had been struggling to pass. That was only possible because I had carefully watched and learned her routine. Often with egg binding, it worsens as they work and work to pass it and exhaust themselves. They can run themselves so into the ground that they no longer have the energy to try and having an egg they can't pass becomes an emergency quickly as it keeps them from pooping. Letting her continue to exhaust herself overnight could have really worsened that prognosis. Delaying going to roost isn't a classic sign of a problem, but for her it was odd and that's always a red flag to look into things further. Note how they walk, how they nap, what time of day they engage in certain activities (10 am or so is chickie nap time over here), what treats they never refuse. The more of these patterns you can identify, the easier it will be to notice when they're "off". That same girl in our flock never turns down a black soldier fly, except when she's unwell. Not finishing every scrap is a sure sign something's up. Our roosters on the other hand leave some of their treats every day, for them it's completely normal and no cause for alarm.

When it comes to checking them in the coop, I would recommend having a helper with you and using a headlamp or having them hold a phone with the flashlight on and directing it where you're working. Keep in mind that the more you light the coop itself, the easier time he would have responding, so you want dim light to get in there and directed light while actually checking him. I often use my phone flashlight to navigate around the flock after dark, and have great success just putting my index finger over most of the light. That way I can reduce it to give just enough light for me to faintly see the floor in front of me, while not giving off so much light as to disturb the sleeping flocks. Once you are ready to look him over, you can use the full light of the flashlight, but keep it nearer his body and directed right where you're working. You know how when you go outside at night and look at something like a phone screen, you're basically blind to everything around you? That same thing happens to roosters. If your light is illuminating the ceiling and uniformly lighting the space, he'll have quite good vision. However, if a relatively bright light is between him and you, he will have a hard time making out that you're even back there.

The main reason I say to have your hands free and a helper present is just in case he were to jump down, or even lose his balance and fall down. You don't want to be trying to navigate that solo and having to choose between using both hands and being able to see him. So the first time you try this, you have your helper, and you'll want to approach the coop slowly, talk gently to let him know it's you (he'll recognize your voice) and open the coop cautiously in case he were to jump down. It's very unlikely that he will, but if he were going to do it he would be much more likely to act as soon as he hears sound outside. So you probably wouldn't even be in there and exposed, you would just possibly need to have a way to get in and get him back on the roost. The vast majority of roosters will not jump down after dark, but I have an odd boy who used to leap into the pitch black the moment he heard the gate open or footsteps outside the coop. He seemed to be concerned that whatever was outside could be a problem and was abnormally willing to rush off blind to defend. It's worth noting, he never really managed to do anything but blindly peck, there were never kicks in these situations, and none of our other boys have ever dreamed of reacting that way. Even with him, this would stop once he realized it was just us. Again, highly unlikely your boy will do anything like this, but just test carefully before you fully enter to be sure he's staying settled when he first hears the sound of your arrival/the door being accessed. We can't know for sure how he'll react the first time, so caution is called for, but odds are very good it will go perfectly smoothly and become an easy thing to do moving forward.

As always, if you have any questions or run into any issues just let me know. I'm always happy to help!