Chris writes "sharp", I said the "whole image circle".
Doing architecture like in the sample I showed, includes sky very often and the corners may be neglected as the contain either sky or some trees or just not important parts of other buildings.
And also: I wrote you can focus the "unsharp areas" nearly perfectly, but because there is a field curvature (astigmatism) nearing the borders it may or may not work to use it.
This is no different than with large format lenses we used the last 150 years on viewcameras. It´s up to the photographer to creatively use these effects and build images that hold up.
About the Leica glass: I once had some Leica R lenses and also tested some:
my Impression is that with the exception of the wideangles, the lenses from 50mm and up were always built like little MF lenses with shorter Flange focal distance, having plenty of excess image circle to be able to use the center sharpness sweetspot.
My favourite fun lenses i use on the HCam Master TS are
1,2 55mm (an old Vivitar sold in Germany as Revuenon) dream bokeh - tilted it´s even better
1,2 85mm Canon FD-L (with Ed Mika mount to EF) THE Portrait monster tilted !
2,0 100mm Canon FD
2,0 135mm Canon FD
1,4 35mm Samyang
2,0 28mm Canon FD
and of course the 2,8/ 14-24mm Nikkor at open aperture tilted at 14mm
Same fun 11mm full tilted with the Canon 11-24mm EF-L
The possibilities are endless. And 10 degrees of tilt are already "A LOT" !
Greetings from Germany