I'm pretty old fashioned too, I used to never check any books while the game is in progress, and I'm only 23.
This stuff certainly wasn't allowed when I started playing chess in elementary school a long time ago, but in fairness, I retired then, came back, and it seems it's common rule/tolerance now. Even now, I still wouldn't bring myself to use a book to lazily check the openings for me. I wanted to learn them on my own, but after hours and hours of opening study, and being demolished game after game in the opening by RHP players who obviously consult opening databases and me having to play catch-up game after game, I feel I may have no choice but to follow suit. I already have for some games, but not for every game like most RHP players tend to do.
Right now I am playing openings I did when I was younger, like 12 years old (I looked up some of my old pencil and paper annotated games then). When I was young, I apperently was notorious for playing out of book openings in which my higher rank adult peers would tell me they were crap, but couldn't explain why. In fact, based on the results I had against other child players, some up to 1600-1700 OTB, I can find no evidence they are really unsound at all. In fact, as a 12 year old, I invented 3 white openings I routinely used that although they seem to lack agression for white, I cannot find any reason for them to be unsound. So now I'm playing/learning some of my own wacky younger creations so RHP players cannot rely on opening thomes.
Interestingly enough, all 3 of these unique white openings all involve a different first pawn push, they are not the same at all. I must of had a lot of time in chess when I was young to do this, I was surprised just how good these new openings could be, especially considering no GM found/pioneered them. If I was a stronger player, I could perhabs demonstrate their potential way better.