[ARC5] Command set Frequency Usage

[Jack Antonio]

A curiosity question.

In the ETO during WWII, how often were command set frequencies
changed? Thinking mostly here of HF and bomber or
transport operations.

I can see from a security standpoint the need for frequent
changes, but were they changed every mission or at some
regular interval?

The answer may be lost to history, but would like to know.

Jack Antonio WA7DIA/4