I've been pregnant twice. The first time I think we had sex once in 6 months, certainly only once that month. We were also using condoms.
Second time was with my now partner, I don't know how many times, at least every second day but we weren't trying. I was on the pill but in hindsight I should have known it wasn't working because, maybe tmi but I was a bit frisky and that is my number one sign of ovulation.