Dependends on the country.
Many chaps I know use the standard of when on an IFR plan they log all air time as IF actual time saying they are using insrtuments to navigate etc.
Canada when on top, night thats ok.
Australia can only log it when actually in side a cloud, ontop or night when you can't see a thing is not counted as IF.
So a typical logbook from 3 pilots doing the same flights the 3 countries with say 1000hrs would be,
UK 1000hrs, 800 actual IF
Can 1000hrs, 300 actual IF
Aust 1000hrs 30 actual IF