DH used the phrase once in a frustrated outburst a few years ago and hasn't mentioned it since, but I suspect he still feels that way.
I wouldn't say we were exactly sex atheletes, but I would say we have it at least 4 times a month - it's not quite every week (sometimes it might be Monday one week and Sunday the week after) and now and then there might be a fortnight or so without, but usually only if one of us is very tired/stressed /ill. Sometimes gasp it even happens twice in a week. And it's been pretty much that way for a long time, even when the kids were small (been married 12 years).
Other than late pregnancy and after childbirth we have never gone months without having sex and I seem to know plenty of women who have done, even when there were no particular health/stress/marriage problems.
I suspect we have different perceptions - I wouldn't be surprised if asked that he would say we only do it once or twice a month, but I do have a better sense of time and memory than him, and I'm pretty sure it's nearer 4 times.
I've never been a massive fan of sex, and he know that, but he still seems to think there was a time we were at it like rabbits and that it's now dwindling terribly, but I think we're doing pretty well.