There is a lot of sample-to-sample deviation in the Jupiter lenses, and some in the Zeiss lenses as well. The Jupiter-12 is a wide-angle lens, F2.8 maximum aperture- unless the focus was way off- is usually good enough on film. The 50mm F2 has much less DOF, focus is more critical. I optimized mine for 8ft to split the difference between close-up/wide-open and infinity. Sonnar focus shift is towards infinity as you stop down. You can optimize for close up work, stop down to F2.8 for good infinity agreement.
If you look at the J-12, notice that 0.9m to infinity is about 270degree turn. This is about 10degrees more of a turn than the Nikon external mount lens. The J-12 focus will stop short of the minimum focus on the S2, comes to rest just short of 0.9, On the Contax/Kiev, it turns just past 0.9m. I just tried the J-12 on my S2 and the same J-12 on the Kiev 3.