The total shares are spread out over 6 voting pools (6 steemit accounts). The original account, then sbi1, sbi2, sbi3,... There are inactive members in all the pools too which helps give more of a vote to those who post at a regular interval (that doesn't mean more posts are better, just a regular interval).

So your voting weight is based on how many shares you have, how much you upvoted SBI, and if you have given any delegations. Then they look at how many times per week you post and figure out what percentage of the total votes they expect to give for the week you will get. If for some reason you post twice as much for a week then this gets adjusted and your next round of votes will be lower percentage, hence why more posts are better for you.

Hope that makes sense. Part of the vote value is due to inactive accounts. If everyone was active the vote value would decrease.