So after scumming for LEMISI a few times to document the problem, I couldn't find any snake-maps. I think that snakes must be a rare result and that I just had terrible luck getting three in a row earlier. Ah well, nevermind then.
EDIT: I just remembered that you can quickly view the whole map by suiciding. The made things much easier. This is an example of the kind of map I am talking about
About 80% of the map is just one long corridor with no significant options. A player will most likely follow this corridor until they encounter something they don't want to fight (in this case, that will probably be the Snake-5 if they aren't on the very cusp of a level up). They will backtrack to look for better options only to discover that there are none. This creates a lotto-style game where the only black space left on the whole map is behind the last discovered monster. Eventually you run out of gas, and/or you attract Rex's attention and you have no choice but to take a 50/50 gamble at getting stuck with each fight.
I know that yu can get out of these situations by prepping Bearmace/Binlor/Magnet: Defend, and in my guide I even recommend this as a way to 'turn off' the dungeon's gimmick, but I'd rather be confronted with a maze scenario that can be defeated on its own terms. An algorithm that creates several self-contained 'mazelet' regions is much more fun and engaging than a single corridor death march.