A timer waters the calendar, not the garden
A tap timer does exactly one thing. It opens the valve at the hour you set, whether the soil is soaked or bone dry, whether a storm is forty minutes away or a heatwave is coming on Thursday. It cannot know any of that, so it cannot act on it.
That is why gardens die on a schedule while the water bill climbs anyway. The fix is not a better timer. It is a controller that reads the soil and the forecast and decides whether to water at all.