Thanks.
The lawn on sprinkler is set by default to 9 in root depth and the perennial on drip to 10 in, but I tried 7in for the lawn and 12 in for the perennials, and when inside the same Flex monthly schedule, they would still show as watering at the same frequency.
The key here is that keeping all the settings the same, when I split the flex monthly schedule in two, with a separate one for the lawn and a separate one for the perennials, they end up at different frequencies (more frequent for lawn), but when combined under a single schedule, they end up on the same frequency. This is why I was asking if this is a limitation of the flex monthly (same frequency for all zones) or possibly a bug.
I do have a Personal Weather station registered on Weather Underground, and this is what I use for Weather Intelligence plus.
Ultimately I plan to try and use Flex daily, but was still reporting the issue in case it is a bug.