Ah I'm talking more about running and gunning here tbh, as I don't Vlog myself but run and gun quite a bit.

If you have no way of seeing the screen whilst the camera is pointed towards you, I understand why you would want to use auto settings. If you had an external screen or some way to see what you're filming, the variable ND point would still stand as it will always be smoother than the automatic dropping of iso/shutter and always allow the highest quality of shot.

NDs in general are a great tool though and right now K&F are selling very decent filters for around £20/$25 on Amazon, so I'd highly recommend checking them out if you can.

Good luck, hope you find your answer.