I'd have to agree with
Rainboe... It's just another old saying. After all, in a perf. 'A' aircraft, what are you going to use the extra runway for? Stopping after V1 or Vr? We had a graphic demo. recently of how inadvisable that is...
Best bit is that if you are using assumed temperature data (most airlines do) on an average length runway, you'll have pretty much the same margins over the hedge using an intersection as if you'd gone for full length.
