One of my zones is definitely only part sun (4-6 hours), but another part is full sun. The full sun part is usually a stressed area. Do you think I should just over water the part shade area to keep the full sun area irrigated?
You can't win here, they need to be separate zones. Either over water and kill the shade or underwater and stress the sun.
I'll assume we are talking about turf zones. If not then you can probably swap the nozzle in shade to a lower flow, possibly?