No, you should still remux. why would you waste ~10-15GB on non critical info.
Bit of a slip: 'of UHD discs' should be 'from UHD discs', that's to say not a rip to ISO but the video+English audio streams+subs, non-transcoded, in an MKV container (which tbf isn't the 'entire' contents but eh, outside of a few language streams it often is, disregarding menus).
That said I have ripped to ISO before but can't remember if I saved 10-15GBs compared to the later MKV transfer even with streams I didn't want excluded, though likely depends on how many foreign language audio streams are included with the particular release.
I'm just glad with storage capacities and prices as they are such things are possible.