So, don't do it. Pay for all of the sessions at once when you go train. DO NOT have an auto-pay every time you rank up, that'd be horrible. I don't know where that idea came from, but it needs to go home. We can agree that's terrible.
When you train, you train for the next x-static-number of ranks. This uses both your money and PP (assuming we still have that). Right now, x = 1. Make it x = 5 or maybe even x = 10.
But there's a problem with that I want hit; the costs. If every time you go train you need to pay for several training sessions instead of just increments of one, it can come to a point where you'll need a lot more stuff before you can go train again. I won't pretend I know how much tria people have at the higher levels ranks, but I know training gets expensive as I go along. So, I'm going to assume the worst case scenario and say that the idea leaves everyone stalled due to funds/PP. I have two ways I'd do this noise:
1. Make training less expensive in their individual costs, train in increments larger than one (adding each next increment cost to the next; example train for 5 ranks instead of the one), but make progress take longer (you need to use the skill more to rank up than before). This'll keep people from running out of money, but keep them limited on how fast they rank up. It also let's anyone who went cash-hunting to go train a skill for x-static-number of ranks and really go deep into the skill and get tons of cash (and PP, if it's still there) for other skills they may want to start into.
This way limits players more on the time aspect than the cost aspect. The more time you spend progressing your ranks, the better you'll be. The more active you are, the better your skills.
But I have another way that may or may not help bring food for thought on the topic. This will ignore everything I have typed above and just change one small aspect of the system:
2. Choose how many ranks you want to train for. Instead of making someone train for a static number of ranks, let them decide how many ranks they can afford/want to rank up in before returning to the trainer. That way the player controls the amount they spend and how much longer they have until they need to return to the trainer. Costs and stuff would stay the same, at that point.
But that's just my take on 'making less trips to the trainer'. As far as PP goes, I honestly think that Volki is right. It's in the way and mucking up what could be a simple, easy system to use that's not like your WoW or EVE (maybe a lil' like EVE, or how EVE used to be, anyway).
You train til' your rank is done (by actually doing the skill), you go to a trainer to buy training so you can get more ranks (with tria, because I don't think you can buy food with PP), rinse and repeat, and that's the end of that. No PP costs, just tria.
General experience you guys are seeing (green number showers when you cut 24 Barberries at once) can be either done away with or somehow connected to the progression bar instead. I have an idea on that, but my post is far too long for a new guy like me already.