I never write thanks specially if we are finishing. If there are no more interactions is simply wasting money. But when adding new messages I almost always start with "ok great, now let's continue with..." when previous job is ok, so I "reinforce" the clanker as much as I reinforce myself in my train of thought.
You soon won't be able to afford to thank if they start decommissioning old models unless you run local. You are literally wasting energy, it's like leaving your care running for a few minutes for no reason.