>>63805901
I suppose it's generally less effort to just do it in meters, for example .4m is easier/faster to write than 4dm because the decimal point is less complex than the letter d. If you then want more precision, you've already got your decimal point established and can just add more digits, such as .47m instead of 4.7dm.
>>63806454
5 feet 7 inches would typically be written as 5'7".