I've never been really happy with the idea that even under intense training, with masters, under ideal circumstances, you couldn't gain a bunch of ranks in an ability. . .but part of me shies from the idea of someone 9th level, but unskilled in unarmed fighting getting into a barfight with a 5th level brawler and getting embarrassingly beaten up, leaving, purchasing 20 ranks of Martial Arts while working out in a gym for a week, then coming back to beat the crap out of the brawler with a stunning display of master level skill.
I do totally get the logic of not being limited to 1 or 2 ranks, for a lot of reasons, but something about learning 20 ranks in one level just seems wrong. . .I admit that often that won't be an issue, since usually players won't choose to do so, but not putting a per level limit in place means you literally, if you happen to be at a level cusp, go from -25 total ignorance bonus to a respectable to high bonus in the metaphorical blink of an eye, which seems kinda crazy. . . .I might be cool with the idea if a PC spends a year or more in intense training to get there, so our hypothetical 9th level above makes 10th, spends a year in intensive martial arts training with masters, comes back and beats the tar out of the bar bully, that makes sense. . .but not unskilled-click-level-master.
It's your house rule, so it must work for you, but it's definitely been an issue I've struggled with at my table, so I'm interested to hear your view on that overly quick upgrade angle.