I consider each time I need to pull out my phone and "do it myself" to be a failure of my smart home system.
If a light cannot be automatically on when I need it (like a motion sensor) or controlled with a dedicated button within arms reach (like a remote on my desk) then the third best option is one that lets me control it without interrupting what I'm doing, moving from where I am, using my hands, or possessing anything (a voice assistant).
Do you not just turn the light on when you go in a room, and turn it off again when you go out? All the rooms in my flat have switches next to the door