@Pohl
That said, I did minimal research (for device support) and no planning, and HA is running my house, which includes 30 or so Z-Wave devices, a couple external cameras, a smart doorbell, my HVAC, and my irrigation system. Some of the systems are controlled by their own software (the bespoke stuff is often much more user friendly than the HA integration controls), but I have triggers for things like the front door keypad disarming the alarm when it's unlocked by the pet sitter and we're on vacation.

You may be right that it's better to plan things, but it's also entirely possible to successfully wing it.
@ilfi @selfhosted