Well, yes and no. That is to say, the sinkhole thing definitely describes some cases (somewhat literally for Ritsuka on a few occasions) but, well, it's complicated. And Ritsuka arguably has far too much experience with this, anyway.

"Oh, that part isn't too hard, if you don't mind working a bit and staying at whatever's available."

Which is to say, she's had to camp out and hunt monsters for extra supplies plenty, too.