Well, I did use the levers for level-scumming a couple of times but got bored of that. It's best somewhere around level 3-5 with the chaingun. The worst monster spanwed is a chaingun former human, so you can usually (95%+ of the time) kill them all before they even become active. And with those former humans spawning, you won't ever run out of ammo too. If you've still got a health globe or two on the level, you can survive for a loooooong time. The most I ever did was getting to about 6/25% on level 5, and I had a supercharge globe nearby. But this gets boring really quick, and levels aren't that important in doomRL anyway, so I stopped. But if someone had the patiencce, they could probably develop pretty much a walking tank in early levels. Plus you get a lot of points for this too, so it's a win win.
