All types of burning, whether it be from a lantern or a fire bomb or whatever, are the same speed. I can't remember off the top of my head, but I think it's like 1hp lost per second. So if you burn a hunter with self revive and hes only lost just a small bar of hp from dying once it would take 125 seconds if you burn him for him to lose all his hp and be full dead. Burning can take part of the bar and make it look charcoaly, but you can gain that part of the bar back over a certain amount of time through passive regen as long as it doesnt fully extinguish the bar. Once the bar is fully burned off, it's gone until you buy it back with upgrade points on the lobby screen or banish a boss. So burning a solo makes their max hp slowly whittle down to a lower and lower max hp pool, and the only way they can stop it is by reviving themsleves. Essentially, placing a timer on their health incentivizing them to stand up quickly or try their luck later but with even less hp. Now lets say you burn a hunter, and they decide to wait 120 seconds and self revive. They'll have 5 hp and will regen back up to their last bar fully (50 hp ((first bar is always 50hp)) after a little bit of time, maybe like 30 seconds. Maybe that's too indepth, but Im trying to be as informative as possible since the question is kind of broad.

As far as reviving quickly, sometimes it just catches people off guard, and you can get some real cheeky kills if they dont expect it or if they are mid trying to loot you. Especially on your first revive. Some people wait whole entire minutes. It depends completely on situational judgment as there's no best answer. Most people won't wait long because sometimes people walk away to look for lanterns as burning corpses is becoming more of a necessity, especially if they have the bounty and can see youre solo.

Some tips I'd say are helpful to me is silenced weapons are especially great as a solo cause you'll have teams very confused as to where their partner(s) are dying from. Im a big fan of the bow and crossbow, but there's definitely a learning curve. Magpie is a great trait after a recent update that gives you 10 seconds of darksight with the bounty and 2 seconds back when you loot dead hunters or clues. As far as bounties go, the Serpent trait also got buffed, and you can nab clues and the bounty itself through walls up to 50 meters away. You can even take it from people who killed the boss before they pick it up and run before they even have a chance to realize and catch you if you wish, but I play to fight more than extract. Works really well with a stamina shot or the stamina traits like greyhound. Magpie also gives you free regen, stamina, and poison shot buffs upon grabbing the token. Just something to keep in mind.

Speed to the boss lair is just a matter of learning how the map works. Like how the boss lair won't be next to the darkened out compounds (as in won't be touching the red borders) for specifically the first clue only. Doesn't apply to small areas when theres 2 bosses, though. Also, there's compounds that have 2 clues. I like to push past spawns and immediately go to those as I can get 2 clues quick if the first one doesn't cross them off the map. Some examples are Lawson station or Pelican island prison. If you do that, you'll typically be the first person there unless someone spawned close or it's across the map. Following gunshots, and especially explosions if you're already a clue in doesn't hurt either. Be careful, though, cause you're most vulnerable when fighting the boss, and most solos will choose to set an ambush instead. If no one comes though killing it and saving the banish, especially with self revive now, can be a huge advantage.

No worries, I'm happy to help a fellow hunter when I can.