potential gaps between log harvests
Logs are currently harvested daily, with distinct non-overlapping windows between harvests. This leaves open the opportunity for log items at the tail end of the window to not be picked up at harvest time, especially if the harvest for 'yesterday' started the first second of 'today'.
Also, counter compliance imposes a lookback period of 30 seconds in order to mark double-clicks (repeat-visit) properly, so this requires new read events within the first 30 seconds of the harvested elements to look back to the previous harvest to know how to count themselves. (And in actuality, the earlier visit seems to be the one that needs to be marked a repeat-visit, but maybe that is only if you are deleting the repeat visits)