Nope, because it's a misc skill. It's more fun to only train minors and misc with trainers, unless you gotten to the point where you need days to raise skill levels. Major skills go up as you use them, and in my opinion it provides a much smoother level up curve. Unless yoga is using redone leveled lists via mods, one won't meet really unkillable enemies.
As for length.. last time I stopped I was done with Tribunal and Bloodmoon, which are paralell, as you put it Japo, so they don't care about the main questline, and don't even remember my level, but ha a solid 150 hours in the game
I had aroun 300k gold though, so I just cruised aroun with my tribunal armor and the swords of Almalexia xD