Isn't the column in a logbook normally labelled IMC not IFR? Subtle difference!
Personally I tend to log only for flight by sole reference to instruments, although if you are half way round an instrument approach procedure and intermittently in sight of the ground / with adequate external visual reference, I just log the whole approach, otherwise you would need to be starting and stopping a stopwatch all the time to count only the time solely on instruments.
We certainly don't log just because its IFR, which most of N Sea en-route flying is.