I am going to raise a query or perhaps a possibility that Whitfield used those hinge blocks only on the safes they made with three or four way throw bolts. Because I don't see them anywhere else.

I spent many years as a metal worker, so although my knowledge of safes is admittedly poor, a cutting torch is not and for those reading this who don't know, tip sizes vary for plate thickness. And, the flame needs to be a neutral one to gain as much heat as possible, in the centre of the tip is a hole through which a high pressure jet or pure oxygen can be injected by the trigger in the torch itself. Once the metal reaches melting point that jet is activated and it literally blows the molten metal away oxydizing it, once oxydized it will not solidify again, but become slag. In the first instance though it does not blow through, but sprays out, with a single layer this is momentary, with laminations however,it is feasible that it wont penetrate, especially if there is a gap between the plates, or a sheet of something else in a sandwhich. Also not all ferrous metals will cut with this method, they will melt though.

Looking at Safeman's photo, which being monochrome doesn't tell all, I would bet money that the first hole cut was the left one, and started top left corner, because you always get a hole, and a nick is visible there, but clearly something was preventing them from cutting through completely as the wash at the base of the holes shows that they used the jet to blow molten metal downwards and away from the hole they were cutting. But my guess is this happened only on the inside layer.

As Safeman points out it does take skill to use a cutting torch, well use one properly anyway. But in the case of a job like this you would continue in that one starting place until you got penetration, then once achieved all the dross goes inwards. It looks in this case that that was only partly possible, so something else was going on.