I'm somebody who unashamedly saves money whenever I can, since the money saved can usually be spent on more flying or on additional toys/books/material that otherwise I couldn't have afforded at-all.
Where to stop BRL? I'd suggest we stop at anything that has a shelf-life on it. A 30 year old Met book should be as good as a new one, but a 5 year old air-law book is likely to be out of date. And the shelf-life on maintenance is pretty clear to anybody who can read the schedule and maintenance log.
P