My routine at the gym has always included a few leg workouts each visit, along with the usual upper body and midsection exercises. A personal trainer recently recommended that I do all of my leg muscle groups in one visit, separate from all of the other exercises. Is this more beneficial or does it really not matter either way?

I heard you should work on each muscle group separately. Rotate them, I guess.

it doesnt really matter...as long as you dont work the same leg muscles everyday (if you go everyday to the gym that is...)

How long have you been working out? If you just started, then a full body workout is fine. But later on, you will want to split up your routine into sections(arms 1 day, back + shoulders another, legs, etc.) This way you can push your body to the limit for that particular section one day and do it again for another section on a different day.

I section my workouts by muscle groups. Pretty much a 72 hour rest and rebuilding for each muscle. My weekly routine is taken from another pro body builder because it looked convinient for my schedule.

Mon:Chest, biceps
Tue:Quads, Hamstrings
Wed:Off, or cardio
Thur:Triceps, shoulders, traps, calves
Fri:Back

Ab's can be done every other day though cause they're an endurance muscle so some people are able to go abs everyday. Hope that helped.