In foundation, you follow a 3 month programming plan to build up to mastery sets.
Let's say, that you have mastered single arm plank and now you move on to planche leans.
What if it only takes you 1 month to master it? Don't muscles get stronger faster than tendons? Have your tendons really gotten stronger? Won't you hurt yourself in the long run?
Also, let's say that it does take you 3 months to master planche leans. Have your tendon actually gotten stronger? Because in a SSC you do the same reps and sets the whole 3 months, in foundation you do 3x6s the first week. So you don't really do high volume until the end where maybe the tendons are getting the real deal.
How does it work?