It takes time to get a share, partially means crunching numbers and not getting it before a block is found. That work is discarded and not taken into account.
Well, but if you account for the shares you get just before a block is found it statistically evens out.
There's no such thing as a partially completed share... If you're mining at 10 khash/s you're basically playing lottery 10,000 times per second.
That's true mining solo, coop mining you get paid proportionally to your shares.
[/quote]
Share = easy block, it is the exact same