HM01 tends to follow this pattern:
They will broadcast 6 groups of five numbers; the next day the last digit in each group will increase by "1" until an ending number "9" is reached (but sometimes only until a 6, 7, or 8 is reached) then the group whose last digit reached "9" (or 6, or 7, or an eight) will be replaced by a brand new group - the new group will (almost) always end in a "1" - and groups that end in a "1" will remain unchanged for two consecutive days before progressing to xxxx2, xxxx3, etc.
Groups ending in a zero are rather rare.
The "new" day starts with the 1600z broadcast each day - it is not unusual to hear "yesterday's" groups right before the 1600z broadcast officially begins. The 6 groups are repeated for 4-7 minutes then each group is separated by a data burst in RDFT - there is software to decipher the data. This repeats until about xx20z then starts again at xx30z til xx50z - these times can vary by a few to as much as ten minutes.
I have heard people talking in SS under the broadcast as well as music or RHC broadcasts - mistakes? I believe so.
Recently the exact same 6 groups were repeated from 6/1 til 6/11 when all six groups were replaced with new groups all at once - this happens from time to time but is rare.
FPE