I think if you have high reject rates and low work utility even with high hashrate. Your shares will be low.
I have almost no rejects (much less 1%) with WP
Now I run with d=128 diff, hashes and shares look ok, but interesting, how guys below me by hashes gets higher shares?
I see, they get as higher as current coin diff is lower. May be they switch d=*** dynamically depends to coins diff?
Share count isnt that important ..share diff is
You submit 1 share at 1024 worker diff
Another one submits 8x128 diff share
And you get more profit or same
Because u submit 1 big share and another guy 8 small shares