[fph]

Weird that we chose these numbers because they have many divisors, and yet no one ever says "it's a third past 10", only "half past" and "a quarter past".

[perilunar]

Be the change you want to see: start using ‘a third past’ instead of ‘twenty past’ and see what happens.

[prollings]

Where I am from it is common to use "20 to" and "20 past" too.