I think it is practical to know both metric and US measurement systems.
It isn't all that difficult - - - -
If one balks at the idea, our (USA) money system is "metric"
Think of 1.00 as the basic unit
0.01 is the centi- prefix (1/100th)
0.10 is the deci- prefix (1/10th)
0.001 is the milli- prefix (1/1000th)
10.00 is the deca- prefix (*10)
100.00 is the hecto- prefix (*100)
1000.00 is the kilo- prefix (*1000)
There are, of course, more prefixes. But it isn't all that hard.
A meter is approximately a yard.
A liter is approximately a US quart
I'm looking at the Measurement page in my Encarta dictionary - interesting reading. It has also made me more aware of differences and that there is more than one kind of "ounce", for example.