It's been my understanding that TfL travelcards can be issued for a
period of an arbitrary number of days up to something like a month. I
think I saw it in a post here, though I'm not sure; I may have read it
somewhere else, like an LU leaflet.

I've never actually tried to do this, opting instead to buy monthlies,
plus the occasional weekly when my usual travel schedule is changed.

However, I'm going off on holiday at the end of this month, so last week
I decided I'd see if I could get one that lasts until my time off work
starts. I asked a ticket salesperson at my local NR station for a 24-day
travelcard, but he was adamant that the only zonal season tickets he
could issue were weekly and monthly. (I noticed he left out annual, but
maybe those can't be bought on the spot?)

Was the ticket clerk right, or was I? I'm a wee bit confused.

Niklas
--
"On her tour of America, Queen Silvia of Sweden asked heart surgeon Dr. Michael
DeBakey why Americans are so fat."
-- The Most Important Events Of 1988, San Francisco Sunday
Examiner and Chronicle