The vast majority of places I have read have said to do it every OTHER day, which gives the sperm a chance to recover and increases the quality of sperm.
I think it's also better from a mental health perspective - if you aren't already having daily sex, then it's a huge step, puts alot of pressure on your partner to "perform" and, well to be quite frank, it just sounds totally impractical.
What do you do if your partner needs to go away for a night on business? Or if you want to visit your family for the weekend? Or if one of you is ill for a few days?