the mc is a chunk of time you devote to cleanse your body, not a way to maintain a regular diet (diet, meaning, what your body eats on a regular basis to live, not a plan to "lose weight). when you're on the mc your metabolism slows way down and you let your body rest and clean it self out. if you go on and off again of food you can cause some issues with maintaining a steady metabolism, you'll have rapid weight gain and loss, as well as unstabel blood Sugar
that may cause a drastic reaction like diabetes or hypoglycemia. so no, it's not recommended to go on and off for 4 day stretches as a regular habit.