JT and others.
Working for a few airlines, without an in-house performance guru, I found this matter a very grey area. There was nobody who could answer the many such questions raised.
e.g. with one MTOW performance provider there were no notes as to how the data, and ET's had been calculated. When in the sim', and performing an ET requiring various turns, the crew still elected to accelerate and clean up at 1000'. This of course now changed the radius of turn and reduced the climb performance. I didn't think this was a good idea, but no where could we find an answer, and no-one in the company had an opinion. Incredible.
I was applying the philosophy that I'd learnt from Jeppe at another company.
Gues what! We then transferred to Jeppe and there it stated that the ET was for 15' bank at V2 - V2+25, and the flap retraction HT. Quite clear.
However, less clear was the sometimes specified HDG??? If you are avoiding the lumps, and start the turn at a specified point, surely you need to fly a TRACK to ensure clearance. Sadly no-one in the company seemed to be concerned to find the answer. At least we'd cleared up the clean-up technique, though.
There was another company that had the idea for N-1 G/A's. Below max LW fly normal G/A, above max LW fly the ET. Further, they had it that during the ET, take off or G/A, you could accelerate after the first turn of the ET. There were one of two runways where I was very sceptical of that idea. there was still some concrete stuff in front of the nose.
The idea about the spot HT 1500' at 10nm. Remember that the take off performace considers obstacles upto 1500' above the runway. (correct?) How far away is another matter. Anything above that, (The Alps) is for Mk1 brain. Jeppe, for the last company took it out to 30nm. I thought it good idea, unless visual and returning, to climb to sector 25nm MSA and then think about it.