If i may throw in my 2 cents. i'm a culinary school graduate and edible vendor to patients and co-op's here in california since 1996.
For the most potent edibles. rule #1 is use the least amount of butter or oil to trim as possible. you can use a crockpot for 8-12 hours on low or a nonstick skillet or sauce pan on med/low for 1 hour on the stove and get the same exctraction... BUT......
Why do all that? just turn your trim to hash, i prefer BHO cause it's so easy, just make sure to purge it and get it nice and clean to where it's hard like glass, if it's oily it will still work but it's not pure and who wants to ingest butane left overs.
Just infuse your bho or bubble hash into butter or oil and cook with that. Dosing is easier and you know 100% you extracted all the thc, you can see it!! opposed to the trim/butter extraction where you always wonder if you extracted thc and how much.
I have a guy who sells me bubble hash for 10 a gram direct from grower so it's easy for me to bake now, i just dissolve that hash into whatever medium i will be cooking with. each edible needs about .3 of hash for a powerfull high. thats like $3 per edible and it's like triple strength of co-op's, they use .1 of hash most times..
pm me for recipes or any additional help.. i'm very high so i probably made a few vital errors in explaining myself here
oh and kief is the same as hash, just toss it in the butter you're good to go cook with it. i make a great caramel kief that i swirl through my hash based ice creams