How often do you revise your thing placement?

One thing in doom editing that I never seem to be satisfied with the first time is where I place my monsters and what types I use. Almost everytime I make a map, I seamlessly create the layout with few mistakes and can easily visualize what my details are gonna look like in game. Its never the same with thing placement.

Pretty much everytime I load up a map with monsters and health and ammo, and playtest afterwards, I wake up monsters I didn't want awake yet, my healthkits are one room too far, some sections of a map have tons of ammo and others have too little, there may be powerups that just turn out to be useless, etc.

This isn't to say I can't get it right at all. After playing and replaying my maps over and over, I've got quite a few that I'm nearly perfectly satisfied with. And over time, my ability to predict things that happen in gameplay, or expect things to happen unlike what is desired is. Improving, but I've never quite nailed a map with exactly the kind of gameplay I can expect.

Has anybody reach that level of mapping experience? Could you say, study a map on doombuilder for a half hour or so and recognize that its a survivalist, style map, or that there's gonna be a ton of unnecessary health kits toward the end, or that the way monsters are placed, its a very fast paced level?

Yeah, I've experimented with things placement. I mainly use two approaches. Sometimes I do this: I want action to be at the for-front so I place all the enemies first and then back fill items to accommodate the player for each situation. Or I approach it in segments where I place enemies and items one room at a time. I make sure its balanced before moving to the next room. This approach can get daunting if the level is large though because each test requires that you start from the beginning.