I can tell you now the grinding is causing sub-micron particulate that’s getting into your hash which in turn could cause above average water retention even after a freeze drying cycle. Honestly you could wash it without picking out any stems at all as the stems themselves won’t hinder your hashmaking - maybe rip work bags (if you use them, I usually don’t) but they don’t really do anything that will make your hash worse in the end. Although I do appreciate someone putting in effort to give a nice prep to their material before doing anything to it.
You have to think conceptually in scenarios like this, essentially you are trying to trap the sugar on the nug so if you’re grinding up the plant material to sizes near what the sugar on the nug itself will be, you’ll likely have a lot of that showing up in the bags. Unfortunately it can be underwhelming sometimes trying to refine your material like that when you finally get to pulling bags but it makes for a better overall product and a much easier time drying your material even with a freeze dryer involved
Poke through this thread and this thread - i’ve dropped a few gems in one of them (or both?) regarding how I was previously hand washing my material and a lot of info about how I prep it.