I was one of those who went through both the change over to the metric system and the change over to decimal currency in Junior School (Grade School for Leftpondians) so I got used to using both systems. High school was all metric units as was College/Poly/Uni. Once I was out of formal education and the engineering field I switched between systems as and when required. After I emigrated I was amazed to find that even though Canada is officially metric when you live this close to the US border and work in engineering companies who primarily deal with US customers a lot of dimensions/weights/volumes still use the Imperial (albeit US modified) system.
Nowadays I have preferences as to which system I like to use depending on the size in question, for example:
Distance
Less than 1" (25mm) = fractions of an inch, thousands of an inch or sometimes mm if the Imperial size is a bit weird!
Less than 1 ft (300mm) = either system
Above 1 ft = feet/yards
Greater distances = yards/miles/nautical miles (rarely km)
Weight
Imperial system
Volume
Imperial system
Speed
MPH, Knots, rarely KPH except for when driving as I HAVE to use KPH then!
Temperature
Outside winter temps. = Celsius (-10°C is far easier to understand how cold it is compared to 14°F)
Outside summer temps. = Fahrenheit (85°F is easier to understand how hot it is compared to 30°C)
Inside temps. = mostly Fahrenheit
Some things, like temperatures, are just easier for me to recognize/visualize/have a feel for in one system over the other. Weird I guess but that's just the way I am!
