Probably something simple. Verifying and confirming are your most important tools.
Turn off all your sprays or cap heads and utilize your water meter. An acceptable range of water loss should be less then a gpm with all the heads off as much as possible . If the flow is higher then you probably have a leaky fitting such as a marlex.
It's probably all vans and 15 min on a shrub zone around a building will no doubt flood the area. Change out nozzles and implement a cycle soak schedule
No need to over think this just yet. Keep it simple for now