This isn't the requested response, but IMO what most people need to do routine-wise is find something they'll actually *DO* forever. Yeah, *forever*, for the rest of your life. IMO if you miss for than a few workouts per year something's wrong.
In my case, I had to come up with the right combination of cardio/weights/etc. for *ME*, I couldn't get it from somebody else. Even with regard to sets/reps, what works for me might not be right for somebody else and vice-versa.
I've posted my approach to exercise a zillion times before here, so I expect most regulars already know my position on this stuff.
[Note that Accumulator is going on 50, and is in mighty good shape

]
Sorta funny how people see me, and project *their* workout ideas on me: "oh, you must do ..[whatever]", nope... they simply scratch their heads and say I'm "different".
Shoot, just do two minutes of "burpies" every other day for a few weeks. That's more than most sedentary people do by far.
Learn the Turkish Get-Up, which will teach you a lot about how your body is working these days.
Neither of those requires any equipment or much time. So, heh heh...no excuse for not at least doing them if there's no time for a "real" workout.
With any exercise, learn the correct form and don't worry about the weight. "Demanding" is whatever is challenging for *you*.
I'd try to be efficient about it. No need to spend hours working out. If you can do it for a long time, it's not very demanding and you'll find excuses why you can't do it "just this one time..." because you're so busy.
That goes for cardio too. It's pretty amazing how little (hard) cardio is necessary to get in good condition. For this, I'm all about very demanding interval training, but that's just me. If you need to be able to run 20 miles at the drop of a hat, you'd want to train differently. So, what's the goal?
Whatever you do, I'd stick with any routine for a while so you can accurately track your progress. I know people who mix things up so much they never have any meaningful feedback worth studying. Yeah, *studying*.
And if you don't reap some decent results after a few months, I'd sure reconsider whatever you're doing.