Yes, Colonoscopies are too important to not do an excellent prep. I looked up the Boston Bowel Prep Score and 9 is the best score. I have had four previous colonoscopies (not at Mayo) and the reports only said that my prep was "good". That does not correspond to a score of 9 but lower!
As I said, I found the Mayo Prep easier because starting a low fiber diet with daily dose of MiraLAX 7 days before seemed to reduce the buildup in my colon.
And the 4-liter prep came with lemon flavoring, so it really did not taste that bad. I had to drink 12 cups day before and 4 cups day of which is doable.
And they found 3 pre-cancerous polyps (2mm, 10mm, 12mm) after 5-years from my last colonoscopy.
Actually, I find the diet before a PET scan to be harder because one must avoid sugar and carbs.