In VASI days, at airports with a a mix of medium & heavy, there would often be 3 bar VASI's. The big boys flew the far 2 and the little'ns the front 2. I was told by a local XAA man, when discussing the local major airport settings of PAPI's, that the airport management could set them to the requirement for the most common type or the most critical type etc. As there were many B747's there it was the norm for B737's to fly the ILS G/S with 2R 2W down to about 500' and then end up with 3R 1W. It was clear that if you rose up at 300' to 2R 2W you landed long in B737. Thus some used to accept 3R 1W in lower levels, but personally I chose the ILS G/S all the way as reference with the F/O's shouting " 3 reds". This caused much debate with F/O's and even the training dept didn't come out with definitive guidance. It was further confused by the base training TRE's saying you must fly the PAPI's 2R 2W down to 100'.