This is a very long topic, but I'll throw in that I have a 1 hour drip zone, a 30 minute drip zone, and neither has very high flow. Days that all my zones run, watch out! It takes many hours to finish all the schedules.
Since the best time to water is a fairly narrow window of time (not too early to avoid fungus & infection, not too late to avoid heat & wind) a long run time is not desirable.
It would be easy to cut my runtimes in half by running the drip zones in parallel with the sprinkler zones, and I see in this thread that electrically the Rachio can support running two valves at the same time.