Yes, I have done the Schulze Kidney Flush...both with juice fasting AND without. I honestly didn't 'feel' that much of a difference, but the color & odor of my urine became less intense (after the flushes). I didn't have any known kidney issues before flushing/cleansing; I just did it as part of a complete detox.
Excessive urinary frequency is a sign of an enlarged prostate gland...have you had that checked? or do you have any other symptoms that would indicate prostate issues? (I'm assuming that you're male because of your name).