Sensible defaults / presets are extremely important
You learn much better by fiddling with a single part of the engine while the others “just work” than by having to learn a little bit of everything before you can begin making a game.
It’s much better to implement the core mechanics, the levels etc… And only change the lighting, the physics, etc… when really needed
Putting it on while doing something is fine
You don’t need to tell people what to watch