@DakotaCounty, I tend to agree that it sounds like uneven coverage. When I ran a catch cup test on my system I was surprised at how poor my distribution uniformity was even though I have head-to-head coverage. You might try running a test and calculating the ratio of the average of the worst 25% of the catch cups to the overall average. This number is efficiency/distribution uniformity and if you enter it into the Advanced settings Rachio can compensate by watering a bit more.
In addition if your lawn is split into multiple zones then you could get even better granularity by entering separate precipitation rates and efficiency values on a per-zone basis.