Told twice, the second time only the other day -- out of about 10 itins.
My take was that if I wasn't supposed to be able to do it, or if my requests were EXPLICITLY in violation of the rules, their system shouldn't EVER have permitted the re-ticketing I requested. Black should be black; white should be white.
In retrospect, I guess I was pushing the envelope, and the damn thing broke on through.
It's not like the fare rules are particularly transparent. Mine all say "4 TRANSFERS PERMITTED ON THE PRICING UNIT" -- and I never requested more than three. Granted, they were a bit zig-zaggy, but I never did anything I wasn't permitted to do by the agent(s) involved at the time.
I will accept your luck, however...