This set of posts comes from Pastor Mark Driscoll and his wife Grace. The sermon series The Peasant Princess brought up dozens of questions that they felt they should respond to. The result is this blog series: Christian Sex: Frank Answers to Honest Questions.
Answer: Christian lovemaking should be frequent.
The husband should give to his wife her conjugal rights, and likewise the wife to her husband. For the wife does not have authority over her own body, but the husband does. Likewise the husband does not have authority over his own body, but the wife does. Do not deprive one another, except perhaps by agreement for a limited time, that you may devote yourselves to prayer; but then come together again, so that Satan may not tempt you because of your lack of self-control. (1 Cor. 7:3-5)
Most studies say that the average couple is intimate two to three times a week. However, those same studies also reveal that the average husband masturbates himself in private three to four times a week. So, while there is no number that is prescribed in Scripture, intimacy should be often enough for each spouse to be satisfied, which for some can be every day.