Kai and I were having a discussion at the gym yesterday between sets.
We kept coming around to time usage, and we kept using language like "wasting time," "spending time," and so on.
It's a normal model of time. It's what's most commonly done.
But it misses something --
You can't bank time.
Time passes either way. If you're maximally efficient and effective... time still ticks away. If you're maximally screwing around... time still just keeps ticking. At precisely the same rate.
Perhaps a better way to look at time would be, "taking a turn." On your turn, you can do things that range from more effective to less effective. Some days, you've got more options; some days, less.
But spending and wasting time is perhaps the wrong way of looking at it. You're "spending" exactly the same amount of time each day -- 24 hours. The question is what you do with it, on your turn.