It got me thinking. I sort of miss 4th edition in the way that it forced XP purchases based on house, and I'm of the opinion that apprentices get a raw deal, XP-wise. I agree that the arts/spell levels is good, but the notion of "apprentice = 3 season lab slave" is pretty unrealistic. Maybe for House Bonisagus (research! research! research!), but even they have seasons where they publish or study.
Let's look at the houses and how apprentices might get more XP than mere exposure:
Bjornaer: apprentices are considered magi after they express their Heartbeast. They still do the 15 years, but it would be grossly inconsistent to call your filius a magus and still treat him as a full on lab-slave 3 seasons of the year. If you're not needed in the lab, your master can arrange for a book or a teacher or even (gasp) some free time to do what you might want, like practicing Heartbeast.
Bonisagus: early on, at least, the faster your apprentice knows Latin and Magic Theory the better. The first few years of a Bonisagus' apprenticeship would be getting Latin to 5 and Magic Theory to 3. After that, yeah, one season of teaching/year and 3 of lab slavery, unless the parens is doing something else, then more reading Magic Theory for the apprentice!
Criamon: Hard to pin down. I don't see a lot of Criamon being hard-core laboratory users, but I can see them dragging apprentices around to gain mystical experiences. Adventure XP might be common for Criamon apprentices.
Ex Misc: Another hard one to pin down. I'd expect more training in the Ex Misc special virtue(s). At the very least I'd expect an apprentice to get more seasons of Practice than in most other houses.
Flambeau: Less focus on Latin/Magic Theory, more focus on practical training. If you're not using the apprentice in the lab, hand him over to the arms-master for training. Make him practice spells for Mastery.
Guernicus: Prospective Quaesitors need a LOT of training. Awareness, Folk Ken, Code of Hermes, Intrigue, Etiquette, Leadership, the list goes on. Not helping in the lab? Here's a Teacher, get learning. I'd expect these guys to have far and away the best training any house would provide.
Jerbiton: Study magic? Sure, we could do that. Or we could visit Paris. Apprentices get a lot of practice in Area Lore and Social Skills as well as adventure XP (social adventures with other Jerbiton apprentices).
Mercere: Apprentices are family - literally. Combine high expectations with familial indulgence. Stir in the necessary skills to perform as a Redcap if need be. Extra teaching necessary, but there are plenty of Redcap volunteers for this.
Merinita: Less focus on Magic Theory, more on Faerie Lore. Probably not a lot of bonus teaching, but some adventure XP dealing with faeries.
Tremere: Apprentices need to be useful to the house. Probably at least one extra season a year of teaching, if not by their pater, by someone else.
Tytalus: enjoy being miserable. Mastering magic is your only hope of escape. Your master gives you seasons of mind-numbing work, during which you do as little as you can get away with and Practice what you can, Read what you can't practice - just as your master planned. Oh, and your pater sends you on terribly dangerous (carefully constructed) adventures to make you strong.
Verditus: Training is the rule of the day. Your pater doesn't need your small contribution to lab total often. While he makes stuff, you get trained in his Craft.