... the R5 is my favorite. It's a great camera, it's almost identical to my Minolta XD-11 (I think Leica copied Minolta or vise versa). ...
I may be mistaken here, but I believe Leica took the XD-11 design and modified it. In particular, the Program mode differs from the Shutter-priority "program" the XD-11 uses (Minolta never called it a program mode).
As on my R8, the R5's program mode works like this:
Select Program mode.
Set minimum aperture on lens (e.g. f/22).
Choose the slowest shutter speed at which you want the lens to remain at its widest aperture. The camera will evaluate the light level and keeps the lens wide open while trying to select an appropriate shutter speed from the very slowest up to and including your set speed. If none of those speeds will produce the correct exposure, the camera will begin using faster speeds while stopping the lens down.
For example, you can bias the camera to using small apertures by selecting a slow shutter speed. If you select 1/30s for example, any light level where 1/30 and maximum aperture is too bright will then cause both apertures and shutter speeds to increase together.
To bias towards higher speeds, for example, using 1/500 will keep the aperture wide open unless the light level is too high, whereupon both shutter speed and aperture will increase together.
On the XD-11 you select a shutter speed, the camera selects an aperture, if exposure is still not correct upon reaching either extreme of aperture, the shutter speed will be adjusted accordingly (the aperture staying at the extreme that was hit).