I've always wondered the real life equivalent of time involved with a character's leveling of experience.
In our campaign, we have had six gaming sessions that have spanned over four months of real time and has lasted three game days. After the fifth session, we have had one PC death and two characters were able to advance up to second level (barely, I might add).
When one thinks about it in terms of game time, three days of harrowing life threatening adventure was enough to slightly 'advance' two player characters' knowledge and experience. To me that seems to be a fairly accurate process. There was plenty of near-death experiences for those involved, not to mention overcoming some dungeon dangers. It really wasn't easy for any one (1st level) character to survive but most did and the rewards are just starting to show.
We'll see what the future holds for our party of brave, though at times foolish, adventurers.