For self training I suggest to add a bar that fills up (probably blue or orange on this UI) and starts over each time you gain a PL with a minimum timer of 5 minutes. So if it takes 20 minutes to gain 1 PL, the bar fills in 20 minutes. If it takes 1 minute to gain 1 PL, the bar fills every 5 minutes for 5 PL gain.
It can be canceled at any time for the current amount gained, but takes 5 minutes after you click stop for you to be free to take actions. So you can’t use it to immediately react to things. Once you click stop training, those 5 minutes you have to wait don’t count towards training time (small benefit to choosing the appropriate time to train, too). Or alternatively you don’t even need to choose a training time, just click start training, it increases the longer it goes, then click stop training. Just make the limit between 8 and 48 hours, depending on what balance you want (or, again, increased maximum time can be something earned).
This messes up the longer training = more PL per hour. I suggest every time the bar fills, your PL gain increases slightly, simulating the same effect of longer training is more PL. Whatever numbers make it fit closely to current, or adjusted to whatever you like.
I would do something similar for things like time to learn moves or anything you have to wait around for. For moves maybe even a way to gain the ability to queue them up, either based on total time or total skills being learned. You’d need a way to pause the skill gain so you can even stack more than one, but I think that would eventually be good functionality. Or maybe you can start training a move and then queue up a training session when it finishes. This can be just regular game functionality or mechanics and QoL you earn as you progress.
A bit of movement and animations on the screen will do a lot to add to the feel, in my opinion. Along with training being a bit of a stopper for playing right now, especially if you change your mind. Suggestion: Make the bar that fills nice and thick and juicy, relative to its size and position in the UI. Not a thin little bar.
Edit: If you do ever want mini games or have areas you want players to be able to fight enemies for however long they want without limitations, but not give benefits to active player strength for playing more hours, those types of activities could translate to benefits like what I’m talking about for queueing timed things or increasing max training time, things that are nice to have and make it more fluid, but don’t directly increase player strength.