The daily payouts vary due to several factors. The number of posts and comments created each day can vary (days with more content creation mean more rewards distributed). Changes in curation activity can affect daily payouts. If users with significant HP vote more on certain days, this can increase the total payouts for that day.
How does that sync up with the pool being given a set amount of inflation each day?
My question is, if each day's inflation is roughly the same, how is it that each day's payouts can vary so much?
It appears that an ~8% variation from day to day is common.
Do daily payouts go into a pool that smooths out daily fluctuations in rshares voted/posts to vote them on?