My sole guess is that Rabiat thinks levels with special entrances are somehow harder than levels without such entrances. As for whether savescumming results in a lack of special level entrances, I think that you simply got unlucky. Maybe you died on maps that did have the special entrances before you found those entrances, and survived on maps without them, making it look to you as though they weren't showing up because you were scumming rather than a simple coincidence. I propose a test: make sure to save at every single level, then just before you reach a depth where you expect to see a special level entrance, save, then copy the save, then use the copy(ies) of that save to see how many maps you can survive, and of those times you survive how many had special level entrances. 20-30 might make a fair number for number of maps survived; 100 would give a more definite picture but would also be time-consuming. If, say, only 1 or 2 of the 25 maps you lived through had a special entrance where you'd normally expect about 5-10 to have it, then there may be something funky going on (though whether it's specifically because you're scumming still looks unclear from this experiment alone; it may be that certain parts of the level range don't have an equal chance of spawning an entrance by default, or it could be the fact that you're playing on U, or perhaps something unknown).