I have a different experience.
I got stopped up and really uncomfortable on b+p shakes, and I switched to Parastroy.
Parastroy has cascara sagrada in the Pararid pills.
The program is about 3 weeks long, and I completed it. (I did not pass anything that looked like worms or spiders.)
Its been 1and 1/2 weeks, and I got back on p+b shakes, I'm not stopped up, and I have started to pass plaque.
No ropes yet, but pellets and folded in pieces along with other bm's.
Somehow I think it worked okay for me.