Agreed - but that doesn't mean the 1000 ft in front of the TDZ are not suitable for the ground run of an aeroplane. If you land short, you're still on a load bearing surface of just the same quality as that of the TDZ and beyond.
Of course it doesn't but would you land short or are you supposed to to aim for touch down point after visual transition? All the RWY left behind bears no relevance and it can be 1000 or 3000 ft. It's gone and is not part of the equation. Certification data have got nothing to do with a landing at a particular airdrome as the TCH can vary. The problematic of application of ALD used for certification on daily basis is well known and is addressed by both airbus and boeing, by issuing more realistic operational landing distances. However the original question is when would you use GS figure and the answer is whenever it's published and ILS or PAR is followed.
