It increases anticipation
When lovemaking is kept on the front-burner, it builds anticipation. Both husband and wife begin to prepare for their marital recreation.
Have you ever thought of sex as recreation? It is! God gave us the gift of sex as a form of recreation in our marriage. It's our own private playground where God intends for us to enjoy physical pleasure.
When sex is on the schedule, we enjoy planning our time together, because we both hold the same goal. We can even become a lifelong learner of giving pleasure to each other. Keeping a couple of Christian sexual technique books on the shelf may develop us into connoisseurs of giving physical pleasure to each other, and it builds anticipation as we think about the next time we'll be together.
It allows for prime-time planning
He prefers nighttime when he can be romantic. She prefers daytime when she's not so tired. They decide that twice a week lovemaking is on their calendar—Tuesday at noon (he comes home for lunch and she arranges a sitter for the kids) and Friday at night (after a warm bath and an evening of watching a movie together or going out on a date). This schedule worked well for one couple we mentored.
Most couples not only differ in their desires concerning frequency of sex, but also in the atmosphere that's conducive to sex. Some struggle with making love anytime children are in the vicinity. Others prefer a certain time of the day. When you put your lovemaking on the calendar, you can work to accommodate those likes/dislikes to meet the needs of both.