The scope of the ‘not’ is also unclear here. I think they’re saying that you waste time if you don’t do all the things in the list, but it could also be read as

The scope of the ‘not’ is also unclear here. I think they’re saying that you waste time if you don’t do all the things in the list, but it could also be read as saying that not using the debugger is a waste of time, and that adding debug log statements and writing tests is also a waste of time.