Custom x_unit with timeline

I would like to create a customized x_unit in timeline view something like a shift. For example a morning shift from 8-12 and an afternoon shift from 13-17.
Is that possible ?

probably you can skip unneeded hours from the time scale,
check this article

Thank you for your answer.
I have tried the custom scales by ignoring hours and it’s not exactly what I want.

Is that possible ?