I wore shorts in china and it got down to -12 deg C however that was not by design (I didn’t take any tights with me).
now back in the UK I have been using bib tights through December and January just through comfort. Bib tights do wind me up – how do you go for a leak without stripping off completely!
I am not sure there’s any connections between cold knees and them not working?
I agree in part with the statement that you just pedal faster to keep warm however if you get stranded or need to fix a puncture you can get cold very quickly.