Well, yes, they serve a purpose in that it's a 'token' to admit you to the ground. But, all I'm venturing is that the club knows that anyone turning up with a 9-23 game book will be entiteld to enter for games 1-8 too, so they will let them in on that basis. Perhaps they'll issue a temporary replacement ticket at the turnstyle just to comply with any heath and safety regulations that insist on you having a piece of paper as proof of entry.
At the end of the day I've no idea, just having an educated guess at why the club haven't deemed it necessary to contact everyone who has one of these rogue ST books.
That is all.