They say to mix for 20 minutes. IMO- that's to long. You end up with to much plant material in the end.
Hang your bags with a rope. let them filter on there own to the next bag.
The more green your hash is the more unwanted plant material you got in it.
IMO-run your first batch mixing it a little. Run that same batch again mixing it more this time.
You'll have a high grade first run, and a lower grade on the second run.
You can also throw your weed in the freezer for a while.