I personally wouldn't go smaller than 110 unless it was to clean up my sift. Basically the way it works is.
You use a micron size like 220, if you are happy with it, enjoy it. If you find to much plant matter or you wish to refine the kief into different micron sizes. You would take the kief from the 220 and use say a 150 micron to refine that. Then if you wish to refine that, use the 110. then 90, then 75, then 45. I personally stop after 45 but some do 25 as well.