Wasted time... well I think this is the one point where I disagree with Ripptoe, the idea that it is always best to progress as fast as possible and that programming which slows progress down on purpose, or by accident is a waste. Sorry in my experience it can be a very bad mistake to proceed as fast as you can if your frame is not build to the same standard as your muscles are. And I think older trainees especially would probably be well served to make progress slower than they could.
If I remember correct, Zatziorsky stated that in the old days russian lifting coaches followed what he called the golden rule of "three years". Three years of proper preparation before you a ready to start a full force lifting cycle... (I would have to look up this...)
Personally I wasted more than enough time proceeding/progressing faster than I really could (that is all of me, not just my muscles)...