Re: How many "quality" hours should I train outside of class?
Not sure what you mean by "quality".. If you're referring to the comparison "quality" and "quantity" which is in some physical training guides (I prefer "intensity" and "volume" instead, but that's just me, because I think all training should be "high quality" or - of high value.
I know of a couple of national team rowing programs where the athletes, who are doing essentially the same movement over, and over, and over, and over (you get the picture), put in as much as 4.5 hours per day of "training" - that's excluding the warm-up and recovery time. I know that I wouldn't survive this training (maybe 30 years ago, but not now), either in Aikido or rowing. Like Rocky in other posts, it takes longer to recover from the hurts.
If you're speaking of general conditioning, that's entirely up to you and your free time. Club level rowers all around the world practice twice per day - AM before work/school for 75-90 minutes of endurance or interval training, and PM after work or school for 75-90 minutes of either endurance, interval, cross training, or strength training. This means being on the water at about 5:30 AM-7:00 AM and again from 6 PM - 7:30-8PM. Not for the faint of heart.