I've enjoyed using the Leica and the Summitar in part because it has encouraged me to look more closely at the era in which the camera and lens were produced in response to the challenges met by the camera and lens designers in those days. The issue which came to the fore in the late 1930s was lens speed. The good quality lenses up to then such as the Tessar with its four elements in three groups were typically capable of being stopped down to f3.5. In the post-war years Tessar designs became available which enabled an aperture of f2.8, but that was the ultimate limit permitted with just four elements.
One reason I have not made more use of the Jupiter 8 is that I also have an excellent Jupiter 12 for the Kiev IIa; it is a copy of the Zeiss Biogon 35/2.8 which often seems a better fit with my way of seeing the world.
I recognize that my frequent preference for the wide-angle 35mm lenses is likely due in part to habit rather than any innate superiority, so I am going to make a determined effort to give the 50mm normal lenses a better chance to show their capabilities. That goes not only for the Jupiter 8, but also for the extraordinary six-element Schneider-Kreuznach Xenons on my Kodak Retinas.