At its worst, I could spend 2-3 hours with it on a weekday. Maybe an entire evening for several days or more at a time.
I don't drink much, never got into smoking anything, never popped any recreational pills, but porn can suck me in pretty easily and quickly. I lose all sense of time. My mother drank my whole life. My cousin drank himself to death. I do porn. Or used to. I've been able to cut way, way back and haven't jerked off in over 14 weeks.
Just think how much better off I'd be if I spent all those thousands and thousands of hours over the past 30+ years doing something productive.