If you wax it too often, like every week, or even once a month, it can lead to a build up of wax. Now different types of wax will last different lengths of time. Some things will effect the length, such as weather. Personally, if you want something to last as long as six months between waxing, I would go with
Poorboy's World EX-P Pure Sealant. I loved that stuff when I had my silver mustang. It really works great on lighter colors, but can be used on any color. I just prefer a wet look on darker colors, where light colors I go for more of a shine.