I am all over the shop with this. Feet or meters for depth, speed knots, miles or km is fine. Temperature always Celsius. As a builder, timber, building products or room sizes metric or imperial is fine, but for calculations metric. For my car I generally use mpg for fuel consumption. I was born in the 70s so we were taught the metric system, that was until I got into the garage with my dad or a building site with my Uncle when I started work.