An overspeed takeoff can be scheduled with any flap setting for which the data is available.
For mid-flap setting, this might be of use on mid-length runways with spare distance and obstacles
The more obvious use is for (comparatively) very long runways where the WAT limit can be improved for a better RTOW at the minimum flap setting. This is similar to the standard min V2 use of lower flap settings to get better weights.
[ 10 August 2001: Message edited by: john_tullamarine ]