You'll hear different guys set themselves at either end of the spectrum for 'deep woods' hunting strategies. Some call long, some call short. Both ways can be productive.

Number one rule for calling coyotes, in ANY environment, is that you have to see them before they see or smell you. This is a bigger hurdle in 'thick woods' than it is in the open, because they have more cover to conceal their approaches, and they'll likely know where you are by sound, even if they can't see you, LONG before you even spot them coming in.

This presents a big problem when walking into your sets as well. It's impossible to know what is in the woods as you're walking in, so you might get busted before you start, and never know it. Depending on the location, I might set up on the edge, and not walk into the woods at all, and plan on calling them right up to the edge, rather than penetrating into the woods and spending more time walking (avoid the scenario where I can't see the forest for the trees). I also spend more time letting the woods "cool off" after walking in before I start calling than I normally would in open ground, so if a coyote heard me walking in, but didn't completely bail, they might not associate my call sounds with my previous walking sounds. Give it 5-10min after setting down before calling. I spend the same 5-10min letting it cool after my last call series so if a coyote came in and I haven't spotted him yet, it loses interest and meanders off before I get up and reveal myself, educating them.

In thick woods, less calling is more, unless you're using an e-caller. The more you move, the more chance you have for coyotes to spot you because you have. Get in, set down, call a little, and watch a lot. An e-caller can be helpful to draw their attention away from you so you can let it run and worry less about getting spotted calling, but it also means you have to walk around more to set it and retrieve it.

How long you spend at each set is up to you. If you only have a few spots to hit that day, you can afford to spend more time at one spot. I'd be hard pressed to ever spend over an hour at one spot. 15-20min is also too short in my opinion. 15-20min per set during a contest is great, where you're relying on volume to win, but if you're just hunting, plan your day to give you a little more time for the fish to bite. 15-20min of active calling is a better hunting strategy, 30min is better. Depending on your walk time, I figure ~40min to an hour per set when I'm casual hunting. Time to walk in, time to let it cool, 20-30min of intermittent active calling, let it cool again, and time to walk out. 15-20min of total set time leaves you about 5min on the call, which isn't enough.

The cooling AFTER the end of calling is probably the second most important part of my calling strategy, at least in the top 5. Putting down a call and standing up to leave will often bite you in the butt. Too many new guys educate coyotes this way. They'll stop calling, give up and leave, then notice a coyote they hadn't spotted yet hauling butt away from them. Or worse, they DON'T EVEN SEE IT, but either way, they successfully educate that coyote.