What advantage does a colon cleanse have over a fleets?

I ‘m going to have a colonoscopy soon. I will have to use fleets to clear my colon before the procedure. I was going to do a colon cleanse to improve the view for the procedure. However, the GNC rep I talked to said he didn’t know why people didn’t do a fleets every once in a while instead of a colon cleanse.
Colon cleansing is typically herbal, whereas fleets is tried and true method