You can also use a heat blanket in sensitive areas.
i have an asbestos pad…sort of like you might have had in high school chemistry…works nice…ultimately speed is your friend, you don’t need to torch the living fuck out of the fitting
I tried when I couldn’t get my shit to seal. A map gas torch with a spiral tip will turn copper fittings orange hot and squishy in about 3 seconds. 
The bread trick is what finally worked for me.
Yeah, if you’re having to apply so much heat that you’re setting beams on fire chances are you’ve still got water in the pipes. Dry copper heats to the point that solder will wick in seconds. Get a slow drip of water turning to steam in there though and you can heat it all night long and never get the solder to melt.
Not sure if this off topic now that we’re talking about PEX and Copper and yada yada, but rain showers suuuuccckkk. With a regular shower head, the water is hitting your back to keep you warm but you can still soap or shampoo up. The damn rain showers, you’re either in the water stream or out and it’s constantly landing on your head when you’re in it. They look nice and all, but definitely not practical.
Yep. It was my first time sweating copper and I really underestimated how much having it dry mattered. Once I got it dry it was easier to solder with the propane torch than the map torch. Now I use the map torch to start fires in the fireplace without kindling. 