I’m on the fence about that.
Personally, I find that some of my exercise sessions are flat out more intense than others. Meaning if I’m not performing well in one exercise, I probably won’t perform in any during that single visit to the gym. I think this is where breaking it up might be helpful (moreso than “afterburn”, which I don’t really subscribe to myself).
From a muscle building perspective:
Clearing lactic acid efficienctly is probably the biggest factor (after intensity and technique, of course). If your body stuggles to clean up lactic acid and expell it (in the form of urine), then splitting up your exercises into morning / evening routines might help a lot.
If you’re like me and have no trouble with muscular stamina and recovery related to lactic acid removal, a longer session all at once is probably ideal. If you’re like my brother (who is bigger, but feels more burn faster and gasses out after 30 or so minutes), you probably could benefit a lot from breaking it up some.
If it were me, I would make my overall goal to set a routine which I could picture myself keeping up forever. Because in all honesty, it’s the active lifestyle that gets you what you want in the long run. So much of exercise is very personal, listening to what your body needs, what works for you, and making changes when you don’t get results you want is fundamental to maintaining the lifestyle.
So, try it out if it seems like it might work for you!
Just because I could talk about the weightroom all day doesn’t mean I know everything. And certainly doesn’t mean I know what works best for you!
I think ideally, we’d all spend 5hrs+ a day lifting, running and climbing. It would certainly make of a very attractive human race, haha!
Short of that ridiculous dream, going about things in a way that is intense, but sustainable, observing proper technique and avoiding injury is pretty much all there is to it.
((I really enjoy talking about exercise, but I think I should throw out a disclaimer:
I am just some random jerk. I have near zero medical knowledge and have little merit to give any advice at all.
If you recognize that you need to make a change in lifestyle for your health, I will gladly provide encouragement. But real solid information and advice is best taken from a real doctor / nutritionist / physical therapist. Individual workout and diet plans are extremely personal and need to be tailored to fit your circumstances, genetics and also account for any medical conditions.
Please don’t read my advice, then run off the rails and hurt yourself. Injury is a very real risk, especially when attempting to ‘get in shape’.))