Tell me about cat anal glands

I have an 8 year old male kitty who started dragging his butt on the couch about a month ago. At first he did it very briefly and I am thinking “is that what I saw him do?” I have seen him do it several more times.

Took him to the vet last week for his annual wellness check, where they do blood work (all good) and fecal (negative). She checked his anal glands and said they were full and expressed them.

Just now, I saw him drag his butt just a little on the couch again.

If they are going to fill up again, how long does that take?

I understand the stuff smells, but I don’t smell anything.

Looking for any ideas before I get in touch with the vet again on Wednesday when she is back in the office.

I assume cat anal glands are the same as dogs.
It completely depends on the animal how fast the get full again. My 14 yr old small dog (more problem with small dogs, most large dogs express them on their own) has never ever had them done as he does them himself. My 9 yr old poodle I do every 3 months maybe.
1 week would be too short IMO for normal anal glands to become full again. Maybe she didn’t get all of it. If you lift the cats tail and feel on each side of the anus, you will be able to feel bumps if they are full (1 on each side, almost just below the anus).
But animals also drag their butts for other reasons. he could simply have had an itchy butt. My 14 yr old mutt will twirl in circles scratching his. My poodle likes to drag and sniff. He drags his butt to itch it then stands up and sniffs his ‘trail’.
Unless he’s doing it quite a bit I probably wouldn’t worry too much.