The frequency is not set. Sometimes once per week, twice per week or even once in two weeks. Sex is a part of an healthy relationship. The frequency of it really depends on the couple involved. However, it must be frequent enough to maintain and regenerate a closeness that only comes with sexual intimacy.
Once a day?! Haha, that must be at least a little telling. Like the others, I think that if both parties are in a loving adult relationship, sex is not the be all and end all. Having said that, it is vital that both parties are satisfied with the quality and frequency of sexual intimacy.
At least once a day.......are you kidding me. The person would have to still be in the first week of their honeymoon. If they aren't, I'd like to know what they are taking in addition to a morning carton of "Up & Go". Good grief, who has got the time for that on a weekday, they can't possibly be holding down a job at the same time.......can they ?