Experience points being rewarded and how they are rewarded and for what will they be rewarded is a hot topic in any forum for rpg gamers.
Most of it has to do with wanting to savor the action and adventure of the low level PC growing into a high level PC.
Some DM's seem to never want to have PC's get above a certain level though and can get, in my opinion, a bit stingy about coughing up the XP. I don't know if it's because they have no interest in finding/creating new adventures that will properly challenge high level PC's or what.
Other DM's toss out XP for just about anything it seems. "Oh, your PC sneezed three times in a row and his head didn't explode. You get 1000 XP for that."
It's like they are just the really giving type or they really want to skip low level adventures to get their players to the really nasty stuff that high level characters get the displeasure of facing.
But, that's their business. I really don't care how other DM's deal with XP as long as players new to my game don't keep trying to compare my methods to their previous DM. At which time I will burn their PC sheet and let them know how welcome they are to go back to that other DM's table.
I give XP for treasure and for the monsters that PC's encounter. I also give XP for how the PC's conduct was handled during the game.
I also deduct XP for PC's who were handled poorly. Yes, I am a vengeful and petty little god. Karma is my favorite tool. heh heh heh
Seriously though, Players who want to game to gain levels aren't really grasping the magic of my game. You don't come to my table to build up high level PC's. No, you come to play at my table because it's about playing the game and having fun role-playing,. solving great mysteries and whoopin up on the bad guys (or the good guys if you are playing an evil aligned PC).
The level ascension will happen in due course. 'm not a stingy XP miser of a GM. I don't think I end up being a Daddy Warbucks type either because oh yes, I will take back 4,000 XP and have an ox fall out of the sky and land on that PC's head if they have it coming.
(Did I mention that karma is a real B in my games?)