I don't think you need to make another step out of decarboxylating the weed. You will know know then the extract is potent and decarb has happened if you look at the weed simmering after 2-4 hours it will get a mushy look and change color. You should simmer it for at least that long. I go for 5-8 hours in total with great results. Always with water under the butter, in the same pot.
last go around i used 75grams of 'frozen' popcorn, 2 sticks (8oz) of butter, water in a crock pot on low for 8hrs- drained it thru a spaghetti strainer , poured add hot water on the 'puck' to get as much butter out as possible.. then into fridge overnite, drained the dirty water, poured clean hot water on it stirred, back into fridge - did that '3' times till water was clear.
the result.. came out with 97grams, bit less the 3.5oz's , so lost over 50%, n the butter was weak...
could it be because i used frozen popcorn???