Warning, inefficient person posting.
I have a bit of a theory which is that inefficient people are "off" by default and have to make a big effort to switch on, it's not like there's an automatic point at which we start doing things. Whereas super efficient people are "on" automatically, and when they are finished, yes they relax, and I think it's probably a nicer kind of relaxation than the inefficient person, and crucially they know how long they have to relax FOR.
I didn't realise this until some time last year and I've been trying to enact it in my own life but I haven't been very successful yet.
This is twofold. Firstly I have such a backlog of things to do that I feel like I could never get on top of it. Certainly, I could never get on top of it in one session. I'd need breaks, and it would take me more than several days. I'm terrible at prioritising. If I was to write a to-do list, which I occasionally do, it involves everything from regular things I'm supposed to do (Take the washing off the airer) to vague thoughts I've had (research buying a guitar), long term projects (start folder for keeping track of classes I teach) and important things I've been putting off (make dentist appointment, overdue since September) - and probably lots of other different types of things. I don't feel like I could ever achieve everything on my list, which in some ways is good - I'll never get bored! - but is also frustrating, because it means in some ways that my mental to-do list is where my good intentions go to die, and most of the things on it just languish there forever until they are so overdue that terrible things are happening. If I ever try to write down every single thing that I need or want to do, it takes up several pages, which is such a draining and depressing experience that I do it maybe once every three years, and cry and try to re-evaluate my entire life but it hasn't worked yet.
Secondly, even on the rare occasion that I feel like I have finished everything which needed doing today, sometimes it turns out that I've totally forgotten something important. Probably because it got lost in the fog of good intentions. This happens just often enough for me to never quite relax anyway, because there's always a nagging thought that I might have forgotten something.
But yep - once I've "switched off" then I'm switched off. I don't think about the next thing I need to do, I don't sit down and think "Ah I've got four hours, I'll watch some TV", I just think "Oh what's on?" But DH who is a much more efficient person than me seems to see his time in terms of blocks. If he's going to relax then he knows exactly when that relaxation period is going to finish and how much of it he has left at all times, like a lunch break from work.
When I remember this and approach relaxing times as a "timed break" then I am more efficient, it does work. I just have trouble not automatically slipping into that old pattern of ah, I'm done/home/kids in bed, time to relax and assuming that the relaxation time stretches out infinitely in front of me until the vaguely distant time that I'm needed again.
The other good thing about the timed break approach is that you actually end up in the nice, better, efficient-person relaxation space rather than the guilt-laden inefficient person's relaxation, which is always tainted with the fear that somebody might remind you of something important that you have forgotten.
(Sorry this ended up so long. I'm apparently inefficient at typing, too!)