I sometimes ask early in the boarding, then the FA moves to a different aisle seat. No difference to subsequent boarders.
But beware if it’s an actual exit row. On that case the FA has usually asked the aisle seat passenger to move to the middle seat temporarily, meaning that the aisle seat is not available to you.
Have done this twice recently, and the FA holds the aisle for me. When boarding pax towards the end asks the FA if the aisle is available, they say it's taken but that the middle is available (where I'm currently sitting); they walk right by.
