We used to have this feature in previous firmwares, but ended up removing it, because the ability to leave a station on indefinitely is unsafe. So in the current manual station run feature, a timer is mandatory, to make sure it won’t be left on forever.
In the current UI, when you click on a station, a ‘manual run’ popup will appear. You can click on Hours + once to set a 1 hour timer, then submit. So we are talking about two clicks as opposed to one click previously, which I think is still pretty convenient.