Dont forget every share is not same, pay attention for example share found at difficulty : 1000mhs and 10Ghs. The share you found at 10Ghs has 10x more reward than 1000mhs.
That doesn't matter, the pool counts every share the same based on the stratum difficulty. The only time the share
difficulty matters is if it solves a block, then the pool submits it to the blockchain and credits the miners. But it
usually means nothing special for the miner that found it.