I studied for 3 weeks and ended up taking 1 day completely off each weekend, and doing a few hours on the other weekend day (I intended to do a half day or whole day those days..but life got in the way). I very much surpassed my goals score-wise, and felt very prepared going into the exam - but I might be the exception rather than the rule.
In addition to taking into account how far you have to go and how long you have to study, I think it depends a lot on your stamina for studying and your attitude. If you're someone who is used to studying a lot, you might not need as much time off as someone like me who generally kept up by going to class but didn't study a lot day-to-day except in the few days before an exam. If you tend to be kind of obsessive about studying in a way that makes you feel overwhelmed and hinders your performance in the end, you might find taking a day off a week helps put things in perspective. Also, if you are very efficient with your study time and can get by with fewer hours, and like to have time to just relax and be a normal human being (I like to think this kind of describes me), you might be able to afford more time off. I don't think taking more than 2 days in a row off is the best idea -- it seems like it might be difficult to get back in study mode after a longer break.