HNTR v. ITYTD
I tend to play ridiculous slaughter maps on HNTR. If there are too many monsters around I take too much damage, and die. I'm pretty sure this is something to do with reaction time - I get on better if I speed the guns up a bit*
Anyway recently maps have started appearing that are too hard even on HNTR. I would consider this a bug. Of course the author will say, "drop the skill level down to ITYTD." However, I believe ITYTD is broken. There is no difference between it and HNTR that the map author can affect - the only differences are that (a) you take half damage and (b) your ammunition is doubled.
Now, dropping down from HNTR to ITYTD usually is for the half damage. This makes a surprising amount of difference. Archvile blasts hardly hurt at all. You can even eat a rocket from a cyberdemon, and, instead of it leaving you pretty much dead (if not dead outright) you still have the chance to go "aargh" and run off. Or, to put it another way: every health item you pick up is effectively worth twice what it usually is. Medikits give you 50%. Soulspheres, 200%, and so on.
The problem is with the doubled ammunition. A properly made map will have enough ammunition on any skill level to kill all the monsters. Therefore having double ammunition completely unbalances the map; you have so much ammunition it is effectively almost unlimited, and you can play like a complete idiot and get away with it.
Furthermore, and more irritatingly, every pickup you make is likely to maximise your ammunition, and waste a fair proportion. This is especially the case if you don't have a backpack. If you start the typical level giving you a shotgun and box of shells, they are now worth 40+16 and you can only carry 50. If you accidentally pick up two boxes of shells, that's 30 shells wasted. I find this greatly frustrating.
ITYTD is broken and a map forcing you to play it on that skill is equally broken.
* Not to the extremes of the super weapons patch, which completely unbalances the weapons obviously (the BFG and super shotgun are many times as powerful as anything else) But when I was fairly new to the game I made a patch that sped up the guns a little but still tried to preserve their balance. It worked quite well and back then made UV playable for a keyboard-using newb. Nowadays it works quite well for slaughter maps.