Ok my new beliefs about blister prevention, after three weekends of backpacking for eight hours a day, and watching a bunch of YouTube videos:

• blisters are caused by layers of skin delaminating, not "friction" / heat directly, though typically the delamination is due to static friction on the outer layer of skin, combined with wet skin. Dynamic friction is more likely to cause raw spots / wear straight through the skin.
• popping them as soon as you find them is basically always the right call unless you plan to be able to avoid the activity that caused them for a week; otherwise they just keep growing as you continue to do the activity
• blister donuts and moleskin work okay as long as you can keep them in place somehow, but they don't stick well on their own
• leukotape, very very widely recommended, is worse than useless because the adhesive seeps through the tape and makes your skin stick to your socks even more tightly than it was before.
• toe socks are pretty good
• KT tape is very good
• Vaseline/similar is pretty good as long as you can get it to stay in the right spots