I told myself it would be an evening. A small Home Assistant instance on the lab, a couple of lights, prove the concept, move on. That was several weeks ago, and I have since lost more evenings than I'd care to admit to YAML files describing the conditions under which a hallway light should turn itself on. I regret almost none of it.
The honest reckoning, having come up for air, is that automation splits cleanly into two piles. There's the stuff that genuinely improved daily life, and there's the stuff I built purely because I could, which is most of it. Knowing which is which only became clear after I'd built both.
The things that earned their keep are dull and I'd not give them up. Lights that come on at dusk, calculated from actual sunset rather than a fixed clock time, so they track the seasons without me touching anything. A notification when a door's been left open too long. Heating that backs off when the house is empty and warms up before anyone's home. None of it clever. All of it the kind of thing you stop noticing precisely because it just works, which is the highest praise an automation can earn.
The things that ate the evenings were the elaborate ones. Multi-condition scenes, presence detection that tried to be cleverer than it needed to be, a dashboard I redesigned four times. Great fun. Marginal value. I learned a lot about Home Assistant's automation engine building things that, in the cold light of day, save nobody any time. That's fine. It was the hobby, not the chore. But I'd gently warn anyone starting out: the platform makes elaborate trivially easy, and elaborate is rarely what actually helps.
What kept me on Home Assistant specifically, rather than reaching for one of the cloud ecosystems, is that it runs locally and it owns its own state. The automations execute on a box in my house. They keep working when the internet's down, which is exactly when you most want the lights to still respond. Nothing phones home, nothing depends on a vendor keeping a server running, and if a company decides next year to discontinue the product, mine carries on regardless because it was never theirs to discontinue. That last point matters more to me than any single feature. I've watched too much consumer smart-home kit get bricked by a back-end being switched off.
It's more work than buying into a walled garden, no question. You assemble it yourself, the YAML is unforgiving about indentation, and an upgrade occasionally breaks something and costs you another evening. But the result is a home that responds to its own logic, on its own hardware, answerable to nobody. For that I'll happily lose a few more evenings.