I believe how frequently you train is related to the routine you use and how long you train each time you do. My workout schedule is six days a week. I train each muscle group once per week with the exception of calves, which I train twice a week. In the routine I currently use I train with weights from :45 to and 1 hour. Then I do about :30 of cardio. Maybe because of my age, my body needs more time to recover, so training each muscle group once a week really works great for me. However, I do sometimes like an extra day off just because I feel like I want to do something different. So, just this week I changed my routine up some. Instead of training a specific muscle group on a specific day of the week, like arms on Monday, I train arms on "day one" regardless of which day of the week this falls on. This allows for a more flexible workout schedule. For example, this week I have out of town business on Sunday and Monday. I won't train on these days but I also won't miss training a muscle group by missing a day at the gym. I'll just do what would previously have been Monday's workout on Tuesday.
My workout time may seem short to some of you, but I don't mess around when I am training. I rest never more than a minute between sets, with the exception of when I do leg presses or squats, when I allow up to two minutes rest before hitting the next set of reps. I avoid conversations other than to be congenial with folks. You've all probably seen fellas who chat it up between sets. This is a huge time consumer, in my opinion. I don't have a training partner, which works well for me. There are always plenty of folks around if I need a spot and I like using Hammer Strength, Smith and other machines where no spot is necessary anyway.
Understand that I am not training to compete in a bodybuilding contest, but rather just to stay fit and healthy as well a maintain muscle. Nevertheless I do still see muscle growth using the workout schedule I do. Since retiring from my job a little less than two years ago, my bodyweight has increased by about 20 lbs. while my waist measurement is actually about two inches less, while my biceps went from 16" to 17 1/2" and my quads from 24" to 26" and I appear more cut. So while I have not measured my fat percentage, I would guess it to be somewhat less than it was two years ago.
