Nonsense, it's very readible. You could tell someone who can't code to say "period" for "P", "hour" for "H", "time" for "T" etc. and they'd be able to read out the period exactly, accurately all the time. They would also know how write their own forms of this. Humans can also look at it and know, intuitavely, without a calculator how long it is.

Trying to get them to multiple seconds (incl all the fun with leap seconds!) would be hard.