Not a stupid question, I originally thought 73u was the winning bag but @JoeCrowe explained to me that the 90u is where the caps/glands are collected.
Check out his thread brotha. Nonstop gold and cool microscopic timelapse of the crystal forming. I use his method now.
Save your arms and use a drill. 
Very true, Not every plant is a good hash maker. This recent run I had over around 20 cultivars but dumped less than when I ran three plants of Sugar Belts x PR/BV. I may have over filled the 5 gallon bucket with material too lol
Luck of the draw with each plant. I’m not specifically hunting for those heavy washers but its cool to stumbled on to them and get some extra goodies from the trim.