NFP/ovulation tracking

Anyone who tracks their cycle instead of using contraception...how has this worked for you? No accidental pregnancies? I know how it works that you check when you're ovulating and I've seen advertisements for things like Daysy. So you just don't have sex when you're ovulating right? But what about how "sperm can live inside you for up to 7 days"? How many days out of the month can you not have sex? What do you do when you just really want to? My mom and family are all super religious and use NFP but they all got pregnant like right away, IDK if it was planned or it just doesn't always work and they'll never admit it. Just wanna hear from other people.