I haven't used experience points in at least ten years. It goes back to my days with 2E, when I began to detest the calculations involved and keeping track of numbers during the game, since it was always impossible to remember who did what at the end of the game (we kept track of individual experience totals for each character back then, instead of divvying everything up equally for the group). However, my longest running 2E campaign rarely kept track of XP this way. It was a bit more of a typical campaign, the only oddball being a halfling cleric that spoke every language in my game world (Helenista). That is when I stopped handing out experience and we ruled that every 2-4 adventures, we would raise levels. If I wanted the PCs to move quickly through beginning levels, it was every 2 adventures, and then I slowed it down during the mid-level sweet spot to every 4 adventures. It worked pretty well. It's something I kept doing throughout 3.0 and 3.5. I've never once handed out experience points while running a 3.X game. Nor will I ever do so with 3.PF, which I do intend on running (it's too cool not to, and I love messing with rules like 3.X encourages). I will be taking this rule into the canon for my S&W/Frankenstein OSR game. Depending on how quickly I need to move them along, they'll advance 1 level every 2-4 adventures. Complete adventures, mind you, not just sessions.
What's the side effect of doing this? Well, in OSR games it helps negate greed and murder as a primary motivation. It might be right for a certain character in the game who has that sort of persona, but when that is the main way characters are rewarded it fosters that behavior as proper within the context of the game. I thought to myself - would I want my children (I have two daughters, 5 years and 6 years) playing a game in which greed or murder are rewarded? Easy answer. No. When you take that away, and reward the PCs with level adjustments based on them actually completing adventures, it has the effect of motivating them toward story goals and thinking about what their characters would do instead. Some may see this as "against" an OSR game philosophy. I say that those particular folks have put the game on a pedestal on which it does not belong, and that no game is important enough to argue about or "revere". The "spirit" of D&D is fun. Not how you play the game, not what rule set you use, and not "keeping it old school." It's... a... game. So, with that in mind, I freely adapt what I see fit - and since I had a problem with the moral issues in play with the older XP reward systems, and to some extent the current (PF/3.5) ones, I made the switch to the system I use now, which is the lack of one.