I used to lift for like 90 minutes, 3-5 times a week...now don't know what the hell I did to lift that much and that long! Oh, and I am seeing MUCH better results NOW.
Now, it depends on how I feel. Sometimes I'll want to just bust out a quick workout, so I do Oly lifts...other times it will take me 30+ minutes to work on DL's alone...then I do other stuff on top of it, stretching my workout to 1- 1/2 hours. It varies due to the crowds in the gym and how popular I'm feeling.
Oooooooh, I forgot about that. Add another hour of cardio on there. Actually, I always did cardio FIRST. Because, you know, cardio is how you burn all the fat.
Nevermind the HYUGE bagel (or two!) with fat-free cream cheese I had mid-morning and a big orange juice, then maybe a sandwich for lunch and a salad for dinner. Snacked on a bag of pretzels all day, and had a medium frozen yogurt for dessert.
It all depends on what my goal is at that time. If I'm adding mass it takes about 2 hours because I try to rest at least 2-3 minutes between sets. When I rip up it takes me about an hour resting 30 seconds tops between sets. This is hard when you have to wait on machines or people to stop talking. I wear my headphones sometimes without music on just so people will leave me alone.
Legs are the longest day; always over an hour. I have had good results gaining mass just by resting between sets. Make sure you know what the goals are of the trainee and adjust your time accordingly.