You don't need to live in the gym. My clients typically have half an hour twice a week with me, total one hour a week, compared to the 5-12 hours you're talking about. It's all about intensity.
Doing the same routine on your own it'd be a full hour twice a week, or better three times a week, for 3 hours. You just have to get your arse into gear working properly. That means focusing on - you guessed it - the big compound lifts, squat, split squat, front squat, powerclean, deadlift, bench, row, overhead press, inverted rows or chinups, that sort of thing. No faffing about with curls and crunches.
Athletic Club East - curing iron deficiency
Current trainees' best lifts: ♀ 130/72.5/160 at 68kg, ♂ 205/120/220 at 105kg