What we've got to comply with is what we've got.
In answer to your question, when metric conversion came to Australia I'd just learnt Imperial, but realised the key factor was to be able to visualise the new measurements, so I started holding finger and thumb at 20 mm, 50 mm and visualising 1 metre and in building things, quickly adapted.
I could pace yards very accurately for mesuring post spacing and wire measuring for farm fences and had a lot more problem pacing metres; in fact don't trust myself even now,
I was luck enough (or unlucky enough) to catch the last of Full Reporting in cross country flying, and got to know exactly what 2 minutes to check point looked like, so converting, 5 km to minutes at cruise then practicing on every flight is not that hard, and gives you ample time to make a turn, and why would you wait to the last legal second anyway?