Sure. When it's plausible and sensible. Epic-level character with fire resistance out the arse? Hell, lower-level character with fire resistance? Adventuring on the Paraelemental Plane of Magma where you've prepared for, well, running around a bunch of sodding lava? Sure.
Random mountain interior designed to be a test for warriors? Uhh... Level 9 Bard 4/Swashbuckler 5 wearing the standard Studded Leather armor a L1 character would have, whose only magical item was a cold iron longsword which was presumably the stock +1, who doesn't have resistance to anything? Umm... Nope. Not plausible at all.………
………Some concepts in some situations are simply so patently ludicrous that they simply cannot be handwaved.
This particular puzzle was a glorious example of really bad design. Room slowly flooding with lava due to cannons shooting holes in the wall. This was something that had supposedly been used before by the local population for testing warriors. Uh... Right. They reset it how? How are they planning to reset it after this? Why can't I jump on the cannons? Are they greased? 1 inch wide? They're not really cannons if they are now are they, more like guns. I've got a +10 Balance mod and a +9 Jump mod, I like my odds. I've got 83 HP, why can't I jump through that wall of fire and just soak up some fire damage? I'll use some cure spells on myself later. What, you mean later on in the puzzle after I've solved it much to your chagrin by accident I have to convince this NPC with me to jump through a wall... Of the same kind of fire? That he takes no damage from? What the hell was stopping me then? And this is on top of, yeah, magic antireality lava that does no damage until you're in it. (And no, it wasn't actually magic lava) Nevermind that a wall of stone thin enough to be shot through by a cannon likely wouldn't hold back molten magma very well...
Yes, yes, complaining about realism or the lack thereof in D&D is pointless/etc, but some things are just too much. Selectively hot lava. Any dragon living in a cave with tunnels smaller than it is. Some things just plain are stupid.