18 years of training. 4 gyms. I've watched plenty of folks show up and then vanish. Injuries take some. Boredom, fatigue, or stalled progress take others (a huge number, honestly). Steroids take a few too (they run a cycle, come off, sink into depression, and stop).
My own setup is 2-3 sessions per week. Whole body each time. 15min of stretching plus 45-50min lifting. Rest periods are kept very short — no 5minute tik tok scrolling mid-set or any of that nonsense. Closer to HIIT, though less brutal.
Plenty of routines have crossed my path, and this one came out on top. Beyond carrying more muscle than 90% of the people at my gym — even ones training hard or on small steroid doses — it simply works with my schedule. I walk in, I walk out. No fixed days to plan around, no mental checklist of which muscle group still needs hitting.
Sure, some people genuinely enjoy training. I'm not in that camp. The post-session feeling is nice, and at mid 40s(man) I look better than most guys in their 20s, but the fun is gone and 7 days in the gym isn't happening. There's a life and hobbies waiting outside those walls.
One more thing: splits got pushed into the mainstream by bodybuilders using steroids. For natural athletes, ***full body work tends to win out. Everyone I've coached or nudged toward switching has backed that up — assuming the goal isn't living at the gym 5 days a week (and if the gym is your life, keep doing you). Nutrition and sleep, obviously, drive progress no matter what.
PS. lots of people torch their CNS on splits by pushing too hard (heavy squats, for example) and then trying to return for another session a day or two later.