So it sounds like N is the total number shares in the current shift. I would also take that as the shifts with no blocks have no pay.
The personalized stats recent shifts blocks do correlate with the main stats recently found blocks. I can't correlate the personalized stats earnings log.
You are miss-reading that. N is equivalent to 10 shifts (or at least it was when I talked to PoolWaffle about this a long while ago - should still be).
Furthermore, when a share is found, it pays based on the LAST N shares... future shares are not relevant, so even if N was equal to the number of shares in a shift, a shift with 0 blocks would still earn you something when a block is found during the next shift (because the last N shares would include some shares from the previous shift).
The personal stats earnings log tracks when coins are converted to BTC - there is no equivalent data on the stats page, only the chart and coin totals.