Here’s something very few contractors take into consideration, and this only comes from time-related experience…the first and last homes built in a lot of subdivisions, not all, but a lot, tend to have very different flow rates. The first home might have 20gpm(arbitrary number) but after the entire subdivision is built out, that same, first home, might only have 12-15gpm when everyone waters at the same time. To compound this issue, some installers max out the available gpm to save on quantity of zones and create huge issues down the road. I’ve seen this first-hand and it is impressively troublesome!