I started working out this April, mostly running & light weight training, mainly to recover from my seditary lifestyle. This august, I started eating a lot and lifting a lot, basically trying to bulk up. I know lots of people talk about beginners gains, and I believe I have seen a lot of this, but I have been neglecting my legs, shoulders, and using the smith machine for benching, etc... Im trying to develop a good routine for a mon, wed, fri, sat program that gets my whole body involved.
My main concern is i hear of reoutines where people spend an entire hour on for example, chest, doing around 12 sets of chest workouts. I have not been doing this, but I am seeing results, what happens when I stop seeing "beginners improvment"? Is this really the best way to get hypertrophy, or is this overtraining?
also, im thinking of almost eliminating isolation workings in favor of compound workouts. Is this a good or bad idea?
my last question has to do with machines. All this time, I have been using leg press instead of squats, smith machine for benching, and rowing machines for back. A friend of mine said this is bad because it isolates muscles too much, and the muscles you use to stabalize a normal bar for bench pressing are neglected. Is this true or false?
This is an advanced method of training... in my opinion for people who are pro bodybuilders or have too much time on their hands.
There are programs detailed on this site that suffice for beginners, intermediate, and advanced trainees, and 99% of them aren't like what you describe. (Hint, go digging)
This is a question of goals, again, in my opinion. You can get a very good workout with only compound exercises, and you can get quite strong. If you want big biceps/triceps, you will probably want to have at least some non-compound movements (I don't say isolation because even bicep curls are rarely fully isolating).
In general, I think you're going to want to go free weights. Your friend is right that you don't work as many stabilizers. The more degrees of freedom that you introduce, the more you work on stability (dumbbell bench > bench > smith bench). It doesn't mean it's horrible, just not as good. Also, free weight squats of any kind are some of the best exercises you can do.
Also, one small piece of advice: Since you're brand new, and probably haven't had a chance to create too many bad habits, make sure you work your EXTERNAL rotators and your back.
It's not necessarily overtraining, it just might not be a type of program needed in your situation. You've been doing what you're doing for four months. If you're still seeing results, that's great, but you should plan on mixing things up soon.
Eliminate isolation exercises - If your goal is muscle growth, then I'd say bad idea. Minimize isolation exercises - I'd say it could be a good idea.
Generally, free weights win out over machines. Barbells and dumbbells require your whole body to do more work, which is almost always a good thing. The leg press is a decent alternative and a fine second place choice to squats; Rowing machines are also fine as long as they're mixed in with barbell or dumbbell rows, I'd almost say they're essential; The Smith machine is where I see the biggest problem.
If it's a matter of you not having a spotter, either ask a random dude in the gym for 20 seconds worth of help or use dumbbells. The Smith is notorious for being killer on joints. Even the "ergonomically designed" models with the "realistic 7 degree angle" or whatever it is.
The biggest problem with machines is that they tell your body where to go, instead of the other way around. If you have any kind of joint problem, this will only make it worse over time.
Last thing, I didn't see an exact question about the title of your thread...
So I'll just give you my general take on it. You need to figure out your goals first and foremost. That will let you know what volume (sets x reps) you need per workout, as well as the general reps per set. From there we can figure out the total sets needed, and then we choose the exercises that can hit that volume most efficiently.
So, the number of sets per muscle group (or per bodypart depending on your plan) is really one of the last decisions made when planning a program.