I was wondering if I didn't need all the things UserInputService
provides should I use Mouse
for ButtonDown or would UserInputService be more efficient?
If you're talking about Mouse.Button1Down then I don't really see why not but I'd suggest using UserInputService anyways because if you ever plan on expanding you won't need to convert it and I personally think it's a good habit not to use Mouse Events over UserInputService.
If you're talking about Mouse.KeyDown then use UserInputService. Reason being Mouse.KeyDown is deprecated and honestly, it will probably be removed in the future.
Either would work but on very rare occasions or situations mouse may provide an error, it is very rare but I would still recommend UserInputService just to be certain.