Stormdale said:
I like training fro a number of reasons and have always used it in my games (just coming up to 20 years).
I'll just note as we go along that you could have all of these benefits without requiring explicit level training time.
1. It takes away excess money and magic items. “So you want to train, that’s 250 gp per week. Oh you are short of cash, I’ll take your ring of wizardry instead. No? Well feel free to find another mage in this town with the experience and skills to train you.” That happened two weeks ago in my game I couldn’t believe that the PC was that willing to go up, but I accepted the ring. My players are always short of cash because they have to save up for training, it keeps them hungry for adventure.
My players never seem to have a problem spending their gold. Honestly, I look on this as a bit of a strange reason - if you think they have too much gold & magic...why did you put that much into the game in the first place?
2. As already mentioned it slows down the game. You want get to level 8, that’ll be 4 weeks (I use 1 week per two levels) so the campaign stretches out a lot longer.
Here's another one I see a lot. I think a lot of groups don't think about how exhausting and wearing it would be to adventure every single day for weeks, let alone months or years. We just had 2 months of downtime in my campaign - basically I said, 'nothing big is going to happen fro a couple of months, let me know if you do anything, otherwise we'll pick up with the story later'.
Unless your players are being jerks ("The DM wants to jump ahead 2 months, he must be up to no good! We've got to stop him!") there shouldn't be any problem.
3. It gives the PCs access to higher level mentors for advice, information and potential adventures- not to mention the odd person to be kidnapped by the bad guys and who needs rescuing.
I've never had problems with including mentors, old friends, etc. Someone probably trained them before they started their career, after all.
4. It adds lots of role-playing potential (especially if the PCs are in a new town) as they try to track down a trainer.
I would think that this might get old after a while - sort of like roleplaying out every trip to the market. If I wanted to do a 'search for a trainer' I'd make it into something a little bigger - say, the trainer can teach you the secret of a special feat, or the search for someone to train you in the abilities of a Prestige Class.
5. It makes sense to me. Martial artists don’t automatically level up, they train and train, learning for masters and mentors, then have a grading.
I'd like to note that the grading is an acknowledgement of the training you've undertaken, and not really akin to 'leveling up'. At least, I never learned a new feat immediately upon getting a belt.
6. Not training doesn’t make sense to me. “Gee, I’ve got 6,000xp, great I wake up a new level, oh wait no I wake up as a wizard with 2 new spells.” AFAIK there is no internal consistency to this. If you want to gain a level, or learn a new class in my game you can but it is going to require a mentor, a lot of time and money.
I agree that characters have to do
some kind of training - but to me, the idea that one can adventure for years and never go up a level simply because you didn't go back to town to talk to a higher level fighter - that doesn't make sense to me. 'On the job training' is real - I didn't go to a class to learn shell scripting, I had to start doing it for my job. People learn how to fight without ever going into a dojo (usually by getting beaten up a lot).
Some skills and abilities would need some kind of mentor, it's true - basically, the ones that are marked 'Trained only'. I wouldn't expect anyone to gain a level in wizard without being taught. (Sorcerer, on the other hand...)
I figure that a fighter - or anyone else, really - is training all throughout the course of the previous level. He doesn't just wake up and say 'I've got a new level - what feat should I pick?' He's been practicing.
8. Finally, I like the idea of a campaign stretching over several years or decades, not one or two months/ years, training slows down the calendar and allows this type of progression for me. It slows down the pace of the game and allows for down time. Seasons change and the world becomes more “believable” for my PCs. Rather than having a PC race from level 1-10 in a single year.
You already said 'down time' way back on #2.

There are a lot of tactics that you can use to stretch out time for the PCs, from travel time to 'take time off to rest'. After a week-long backpack trip I know I was more than ready to come home - why wouldn't PCs feel the same way? Plus, camping out in winter is fun for a couple of days but doing it all winter would surely suck.
J