I use the 24 hour clock over the radio and in phone calls.
I use both systems and do not think to convert - it has always been for me 10 meters, 30 feet, 10 yards (I know these aren't accurate but I do minus 3 yards every 100)
Miles and kilometres are likewise
Fluids I use the metric system, I don't like gallons.
I use the metric system in science but have been taught both ways.
I think both systems have their uses, the imperial system is especially useful in the real world because all the measurements are based off things you use/see every day.