Depending on how hard you shake your just gonna force really fine plant matter thru the screen..

Blowing into the tube at the end of the run does nothing but introduce moisture into your bho…
If you think theres more ” goodies ” left.. Run another can thru…

I often emply a quick spray and stop, leave the tube connected, shake, twist,repeat technique before the liquid actually starts running into the collection dish. I’ve never had trouble with impurities getting shaken through doing this. I usually do a strong blow through the tube to get the last bits of liquid out of the extractor.