This is basically Julian Day, which astronomers use. But yes, any humane 'decimal' time system is just optionally giving names to different places in the fract

This is basically Julian Day, which astronomers use. But yes, any humane 'decimal' time system is just optionally giving names to different places in the fractions of a day decimal (I say 'humane' because days have varying lengths, and so should not be used as the basis for a unit used for scientific measures). I still think naming the fractions might be useful (like 'satoshi').