Vaccines were done when we arrived at school around 1960 polio was one not sure of the others you got drops and jabs, each region varied. To the best of my knowledge it was just done. Our children were inoculated a little younger at pre-school age with follow up's.
We all survived these tried and tested methods, no comment with influenza shots since I only ever got one at around twelve years of age, sick as a dog I vowed never again and stuck by that!
New shots it really is up to the individual, my own feeling is one and no more.
Some jabs are required before travel to/from certain destinations, if you want to go take the shots or they won't issue you right of passage.
Personally it is questionable, many never get the opportunity and survive.
I've done the influenza vaccine a few times. Once was my final year in university and they were predicting it would be a bad year. I didn't really want to mess up that because of the flu. I've also taken it before when I have sick relatives and I need to visit them in the hospitals a lot.
These days I don't bother because with everyone wearing a mask and being extra cautious, I haven't been sick at all for 2 years.
The unusual one in Korea is Japanese encephalitis. It's mostly a legacy of the past in here, like malaria or TB. The vaccine is scheduled for kids because parents worry. I've heard it's quite bad if you catch it. I never bothered getting it because it's quite expensive for adults and it's from mosquitos, so I'm only putting myself at risk.
I'll get my booster shot in 2 months, Korea is really strict with vaccine mandates. My wife is an anti-vaxxer and she can't go to restaurants, theatres, museums, etc.
I like to make fun of her by quoting the silliest reasons to avoid it that I read on the Internet, usually the conspiracy theories lol. However, she's pregnant so I'm not going to pressure her to make medical decisions.
Sometimes we have to make individual decisions with what makes us comfortable, being pregnant I agree with her to wait as nothing is ever totally reliable whichever way we go.
Go safely with whatever decisions you make.