Every baby is different.
My ds would feed for an hour at a time and fed 8 - 10 times a day, often attached for hours on end at night (like 6 hours) in the early days. I didn't know any different. He had jaundice & was under lights for 2 days in hospital before coming home, but even weeks after the jaundice resolved he would feed for ages. I got to watch a lot of TV & read lots of books. BUT by about 12 weeks he reduced how long he fed for as a friend of mine suggested bubs do as they age (I was SO relieved when she told me that when my ds was 8 weeks old). BUT, he loved a comfort suck, so I did watch the clock and I'd swap sides after 5 minutes at about 3 months and let him try & fill up from the 2nd side rather than milking the first side for every last drop first. I often ended up swapping back & forth a few times each feed, but overall the duration of feeds shortened by doing this. I wouldn't recommend it in the early days, but in an older bub it worked well for us. By 6 months his feeds were about 10 minutes long in total.
My dd on the other hand is a VERY different baby and would often finish a feed in under 10 minutes, even as a brand new baby! And when she was full she'll just stop feeding, no comfort sucking in sight! She's a super efficient feeder, it's amazing how quickly she can empty a very full breast of milk. I'd say that more than 50% of my dd's feeds are now 5 minutes long max and the rest are under 10 minutes long. In the newborn phase the longest she'd feed for would be 20 minutes and that might be once a day. She'd feed often (2hourly) at times, but she was a super quick feeder. I had no idea such babies existed!