I had my first in the late 70s. Four hourly feeds were the thing (if normal birth weight, otherwise 3 hourly) - 6, 10, 2, 6, 10, 2.
Worked fine for my first (I breastfed) - she’d evidently read the books, mostly slept between feeds. 2nd wanted a bit more frequent feeding in the very early days, but settled into the routine after a few weeks.
Starting solids at 3 months was pretty normal - tiny amounts of puréed foods. Though a Dsis of mine started her 2nd at 2 months - a very hungry baby, going through 2 full bottles and still wanting more. He’s late 40s now, never remotely overweight, always perfectly healthy.
My DM (who had 4) always used to say, ‘Fill them up and they’ll sleep’ - I know say it’s 😱to say that now, but maybe fewer big feeds rather than endless tiny ones does help with that.
As always, a lot depends on having an ‘easy’ baby though - I dare say my DM and I were lucky.
Baby care advice does change - I was horrified at what my MiL told me about stern ‘gospel’ advice at the time, which she thought all wrong, but was too scared/unsure of herself to ‘disobey’. (‘You must not pick them up when they cry!’)
My DM, OTOH would never have listened to that sort of crap.