I think so, especially in truboprop airliners flying between 10,000-14,000ft. I fly between manchester (UK) and Bristol a lot and over half of the turbulent flights with loads of bumpiness I have been on are on these routes, even though I've flown on long haul jet flights more altogether. The answer is yes at the end of the day, aircraft, with their ability to fly above most of the weather these days, well what I just said right there was one of the attractive things about the jet age when it first started. So on shorter flights, turbulence will probably take up a larger portion of them than it will on longer flights, due to the altitude limit.
In a shorter flight the aircraft will stay well within the troposphere and encouter a lot more winds and convection through this area closer to the earth. Turbulence of this sort, in this most active layer of the atmosphere, is far more frequent. Up in the stratosphere, which is reached on longer flights, the air is relatively still, although you can encouter the jetstreams where the tropopause occurs, and if you fly around there, you'll encounter clear air turbulence. But most pilots will make a choice to fly below or above this for your comfort. Of course, yeah the turbulence can affect you anywhere. But theratio of turbbulence levels to flight time, will show that it's more likely on shorter flights at lower altitudes. And I speak from experience! On many of my shorter flights if the plane had been able to fly higher believe me we would have avoided several storms and nasty weather. One time on an F-50 we went right through a cumulonimbus cloud that was developing and it was exceptionally bumpy. Wouldn't have happened had it been a jet at about 3-4,000ft higher
[Edited 2006-07-11 17:10:16]