When 少 is used in someone's name, is it always pronounced shào？
Because shào and shǎo has different meaning. shǎo means few/little, and shào means young. When used in names, it is usually intended to address a young person respectfully. 

As a given name or as a part of given name, shǎo is very uncommon, yet shào is not. 少 as surname is also uncommon.