How old is your baby?
As a newborn, my boy suckled about 45 minutes on 1 side. Feeds are about 2 hourly.
He had a big appetite and drinks slowly, while I've a slow milk flow, so perhaps explaining the long time.
At about 4 months old, he started drinking faster and could be done with BOTH sides in 15 minutes.
I learnt not to time the baby, just latch on and feed until he's fully satisfied.
This reduces need for snacking (very frequent and short feeding sessions)
If baby is bothered by fast let-down, try leaning back while feeding.
Or express milk (by hand is ok too) until fast let-down is over, then latch baby on.
Or is baby going through a growth spurt?
However, during growth spurt, my boy wanted to latch on continuously for up to 1.5 hours, kept suckling and fussing.