I have done over a dozen 40 day MCs and have never had anything but Butt Pee past day 3 for the duration. I have been around this forum for 9 +/- years and have seldom heard of anyone passing anything but butt pee after the 1st 3 or 4 days. If you were doing BP shakes which have NEVER been part of the MC you were NOT doing the MC. The MC on it's own while being a terrific overall cleansing protocol is NOT a colon cleanse
Doing the BPs while MCing basically turns the MC into a colon cleanse and whatever you were passing in mine and many others opinions was the congealed Psyllium and Bentonite. The BPs don't have any laxative properties and if one is not very judicious and drink lots of water it can really plug the system up as happened to a poster a while back that wound up in the hospital with a major blockage. Because of it's highly absorbtive nature it also robs your system of the limited nutrients and cleansing agents of the lemonade diminishing or negating the effects of the MC as it was designed to work. Doing the bentonite while fasting and having an empty system has a good probability of turning into a plaster and really pluging you up.
The SWF will NOT push out any plaque. It is a gentle "rinse" that rinses the whole GI tract top to bottom and not just the lower part or colon. It DOES NOT have laxative properties. That's why the "ideal" is to do the lax tea at night to loosen things up and SWF in the morning. The reason the SWF works is the ratio that it is mixed is the same specific gravity as your blood thus the system doesn't absorb it and it passes through you.
Anyone passing solids doing the MC as per the book recipe and passes any solids past day 3 - 4 it's a very good indication that they have a congested colon and should address that with a dedicated colon cleanse or colonics post MC. Many folks myself incuded will do a round of an oxygen based colon cleanse such as OxyPowder post MC to do a thorough job of cleansing including the colon.