My system wasn't designed by me (keep that in mind.) Street pressure can be pretty high here, in the range of 120 psi at night, hence the PRV. Our lawn sprinkler draw is after the PRV as are the hose anti-frost hose bibs.
I've replaced the PRV twice already...once 4 years ago, once this year, although this year's replacement was due to a crack in the union probably due to shoddy work by the plumber on the previous job. However, I had already noticed some greater offset in DP under load in a PRV that was only 3 years old at the time. I've got sharkbites in it now so that it will be an easy DYI and therefore isn't so f****** expensive to replace in the future. The valves in the yard are self draining, although I also blow the lines out each fall using compressed air on a regulator, cycling through the stations twice per Rainbird's instructions. (Seems to work better than my neighbor's reliance on self draining heads...he's replaced several busted heads each year.) The flat sections still blow a lot of water this way before they blow air. Even with careful draining, I've had to replace check valves to the sprinkler master valve in a previous year, and the master valve body this year when it fractured at the gasket face...this of course ending up being a major hand excavation project since I didn't install any of this and didn't know what pipe I had to work with.