It seems that you can knock out a level in a matter of minutes, even at high levels, by spamming tradecraft leves. I haven't looked too far into it, but considering the enormous boost you get from turning in HQ items and turning in a larger order on some quests, it seems like one could easily figure out a path to 50 in a matter of a few hours (if it would even take that long to run between the leve person and NPC that many times) if they have some allowances saved up, and possibly never even have to craft a single item.
So I'm a bit curious as to whether this is an intended feature. It just feels quite odd seeing this as such a monstrously efficient option to knock out all of your crafting levels with relatively little involvement.