Messy...wouldn't a "third hand" make more sense for soldering work?
-- Lugia

It can, but I've tried a lot of things and like this best.
I prefer using pads like this for any board less than, say, 128x128 mm. Two reasons;
- It's easier than setting up the PCB holder/3rd hand
- I have never found a PCB holder I like. Always something irritating about them, so I use these.

Lager boards, like a guitar amp board, I'll use a PCB holder, but smaller stuff (like eurorack boards) it's so much easier to just hold it on one of these.

and won't catch on fire if the soldering iron gets dropped on it.
-- Lugia

Neither will these. This material is rated to 565 dF, and as you could see at the end of this vid pressing my 675 dF tip against the material leaves no mark or damage. Really high temp rubber.