It feels like it needlessly 'rewards' players for choosing feats instead of ASIs, and it doesn't really reflect the concept you're going for. Whether it's training or practical experience, it should still take time to gain either, so (if you're modelling that in the first place), what you should be giving players is a potential feat or ASI as soon as they earn the XP for it, and then, if they want to convert that into an actual ASI, they need to take X days of downtime, whereas if they want to convert it into an actual feat, they need to battle through Y CR ratings' worth of encounters. No instant gratification in either case.