> Well what you wanted would be a two-level grouping feature: parallel at the bottom level, and sequential at the top level.
Yes, exactly. I would need to be able to define multiple parallel groups like P1, P2, P3 and these groups would need to be sequential to others.
> In your case, you can always set all zones to the parallel group and then just use multiple programs to schedule different zones to run at different times.
Quite often I (or some less technical family member) also run manual schedules. I think this would not work as sometimes you have sprinklers too. Say I schedule manually the water drip zones (then 9 would run in parallel, which is too many) – or it would run together with a sprinkler (which needs 100% water and cannot share).