SnStealth, there is no answer to that question because the concentration of resins in the leaves of the plant varies strain by strain and grower by grower. So what you will want to do is re-extract a second time into the already THC-laden butter from the first extraction.
To do this, after you have gone through all the butter crockpot steps up to where you separate the leaf material from the hot liquid and squeeze it through the potato ricer, you take the liquid and add ANOTHER batch of dried crushed trim to extract, and start all over again.
I know you are going to ask at what point it becomes too saturated to make an nth reextraction practical. I don't know