Anthony Hopkins had around 16 mins of screen time in Silence of the Lambs, yet won best actor that year and anyone who would deny that he gave a memorable performance would be deluded.
Screen time does not equate to a good performance.
What you talking about, course it does. If he won for best supporting actor then fair enough but to win best leading actor for a role which lasts 15 mins is shocking.
Screen time does equate to it hence the different categories, imo