Are there any real-world examples of this, though? I mean a uniform design that either was used for about 60 years, or kept coming back during such a time period?
(In (relatively) modern times, that is.)
I'm not sure if I understand the question. If it's around 60 years, period, the US Army Green "Class A" was used from 1954 to 2015. For more than 60 years, the US Navy blue undress jumper has been around over 150 years. The current USN chief petty officer blue service uniform dates to 1886 (changing from eight buttons to six in 1945). The USN officer dress whites date to 1901, the officer blue service dress to 1919, and the short-sleeve khakis and whites to 1941.