The session length thing was my issue.  I did a little poll here a while back and most folks were closer to 4 hours, I'm at 2.5 typically. (down from the glory days of 4 which was down from the university days of 6)

I am pondering something like "episode based" (e.g., every Full Recovery at end of Episode) but haven't really tested that for how long on average it works out to and it undercuts are more narrative evening's XP value.

I have got used to thing where I give rewards only at certain points (predetermined in adventure creation process).

Lets take an example…in other game, but still it helps.

We played Victoriana RPG and there rules are quite free for GMs to give experience for PCs. There are also luck points (similar to WHFRP points, but I don't remember the name of those atm)…

I made decision that in every "scenario", which is short part of the longer campaign, will be reward of 1-2 experience points (usually playing 1exp scenario took 1-3 sessions and 2 exp scenario 2-4 sessions). I gave luck point based on good ideas, good roleplaying, from the things that helped story go further etc.

Experience points basically were rewards to complete something, not just "trying to survive one game session". Luck points were rewarded after every session…but of course…if PCs have 10 luck points, then I am not going to reward…but things tend to go so that they used most of the points in every session…. (*grin*)

A "session" for my group is 4 hours (ok, well about 3hours of playing and 1 hour of totally screwing around). 

I know you run long campaigns, but I tend to kill off a character or two about every 4 sessions and race through our campaigns..and then say "OK, new campaign next week.  Roll up your character options."

Since The Enema' Wiff-in' is on such an unpredictable schedule for release, i intend to throw this campaign off the rails and see how bad things can get. So far we've got a graveyard of PC bodies piled up and we're going into the final stages of THE DYING OF THE LIGHT.  Bring on the Witch's Song next!