I keep saying I will go to volume for a period or whole body routines but I never get there. Next week I'm thinking just another week of low sets.
I guess what it comes down to is setting your goal or target that you are training for.
Is it strength? Endurance? Size? Definition? Whatever it is you first have to decide that. Maybe a combination of things. Some goals are not compatible though like training for size AND extreme definition. Not compatible.
After determining your goal, then set up your training routine to achieve that goal or combination of goals.
For me, right now, it's kind of simple. My goal is to get stronger in three movements: squat, clean & press, and bench press.
It's simple because it is easily measureable. Success is lifting more weight. Structuring the routine is also fairly simple. Choose a progressive program.
So what "counts" is improvement in those three lifts. Doing more weight in incline flies or dumbbell side bends is ancillary to that. Of course I might have other things going on like "not getting fat" or "improve my aerobic capacity" etc. but those are also subordinate to the strength goals.
Now if my goal was something more intangible like a better physique or " getting ripped" then I would need a different plan.
So you ask yourself the question: What is my goal in lifting weights? How can I measure improvement? How can I measure success?
Most people go into the gym and do 3 sets of 10 and go around to the different machines hitting bodyparts. That's good but how do they move forward from that on a daily and weekly basis? What is the basis for determining improvement? More reps, more weight, looking in the mirror, losing weight, gaining weight, etc?
If they workout for 6 months and then look back, how do they decide if they have improved and moved toward their goal?