Personally I would just resort to weekends. I mean it's healthier for you, less expensive, and at least for me, It makes the week day much easier because I remember things better and it free's up my evenings so I can do extra work. But if you don't want to do that then I would say at least every other day or something like that. Breaks definitely help but it's a hard thing to do when you're used to doing it everyday, especially when you have nothing better to do.