I had a couple of non-ticketed reservations when redating rules changed around covid, and it was a complete PITA to sort out. My tickets went for ticketing under the old rules and arrived from the queue after the rules had changed, so were rejected. And no-one told me, and I found out only a day or two before travel. So I have a pain reflex and a habit of double checking ticket numbers whenever I book, especially if "we'll have to send that off to ticketing, they should issue a ticket within a day or two".

And of course there haven't been any problems since, but it gives you a more comfortable feeling!