The old tube sets would drift, primarily with temperature, you would select the channel, which would get you in the ballpark, but then fine tune for best picture.  As the set warmed up you would have to readjust.

Once the transistor sets came in this was much reduced, and the advent of the phase lock loop pretty much put an end to it, though many sets did not implement a PLL in the UHF receiver right to the end of the CRT era.