But why? Why add a manual, less accurate step instead of just using HA and solving it once? Steaming takes 20 minutes, a quick wash is ~1h, a boil wash more like 4h.

Why do I want only my phone to have a notification? Why do I want it to override other settings and go off at a set time rather than when I choose to interact (as a notification would)?

You can absolutely solve this in other ways, but adding an automation into HA for notifying me about forgetting to setup the dishwasher took a few minutes max and I only had to do it once.