MicrosoftNathan Ziehnert, I think I see your misunderstanding. You may be under the impression that the Smaller Updates contain the reverse differentials for the previous months' quality updates, but this is not the case. Each update contains only two sets of deltas: the ones to get from RTM to that update, and the ones to get from that update back to RTM.
Let's say you installed Windows 10 1809 in September, then you installed the 2018-10 Cumulative Update in October. That update contains the deltas to get from RTM to 2018-10, as well as the deltas to get from 2018-10 back to RTM. Then you installed the 2018-11 Cumulative Update in November. It contains the deltas to get from RTM to 2018-11 and the deltas to get from 2018-11 back to RTM. Windows uses the deltas it already has from the previous update to get from 2018-10 to RTM, the it uses the new deltas it just downloaded to get from RTM to 2018-11.
