Flap setting for take-off depends on type.
eg C150 is 0 deg
C152 is 10 deg
C172 varies with year model as best I can recall
C182 is 0 to 20 deg (20 for short field)
C210 is 10 deg
etc etc
The trade off is Angle climb after take-off vs. Ground roll. At some point the reduced climb performance will have a greater effect on TOTAL distance to 50' than the gain from the reduced ground roll.
Available horsepower to overcome drag will have an effect in determining the recommended setting. I suspect that the C150 / C152 difference reflects the extra horsepower available in the C152.
[This message has been edited by Tinstaafl (edited 08 May 2000).]