Yeah, that 7.5 gal setup is on my list for the fall. I’d like to add additional 1/4" lines for the bigger plants. For that reason, I’d likely keep that at 1GPH. I know that @Modawg2k has a challenge with 2 GPH heads for the runoff reason that you mention.
I always start early-morning. Since I have a yard and garden that I want to have priority, my shrub zone sometimes has to wait until 6:30am or so. If it doesn’t have to wait it starts around 5am. I honestly don’t know if watering shrubs overnight would be a problem, other than at the start I’m guessing temps would be higher than they would at 5am, so you’d get more evaporation.
I rely heavily on the ‘Water Use It Wisely’ recommendations. It’s nice that we can use them to determine how many gallons to deliver. Just as useful is that once you have everything set up in Rachio on Flex Daily, you can also do sanity checks against the recommendations they give you for frequency of watering.