hum, I'm looking from CDG to BRE, that's 338NM - with 737-500, 424 ktas airplanes. First leg says "taxi time 24mn, time airborne 57mn". Second leg says "taxi time 22mn, time airbonre 1h04". So it seems to depend both on airport size and wind.
When editing/creating the route, if you leave your mouse pointer above the "?" to the right of the flight time, what does it say?