My DH's family is like this, absolutely! Once upon a time, he was under the impression that he had to say good bye to everybody, individually, or it wasn't "nice" (yes, we are in Minnesota, why do you ask?
). This would turn into more conversation, which would last for another 30 minutes plus, and so on and so forth. I learned a couple of tricks along the way. Not sure how helpful they would be for the OP, but worth putting them out there.
First, say good bye to people in groups. We go up to a group of people in conversation, catch the attention of one of them, and say, "We have to get going, it was so lovely to see everyone!". This counts, IMO, as telling each of them good bye. The nice part about this is that everyone can continue their conversation after we leave, so there's none of the "Oh wait, I forgot to tell you about the..." comments; they're back in conversation with each other.
Or I will smile and tell DH we have to get going, so that there's topics of conversation left for the next time we see people. "Honey, if we talk about everything in the world tonight, we won't have anything to talk about next time we see the Smiths! Come on, we have to go." This has gotten a lot of laughter and acceptance that the gathering is over the times I've used it.
Lastly, if I'm wanting to leave, and DH is cluelessly chatting away, after having told me "just another few minutes" for the past hour, I will go up to him, tell him we need to go because *insert random reason here*, say good bye, and then I will literally start towing him away. As in, I grab his arm and start moving. I keep a smile on my face, I laugh if anyone sees us and asks about it, I'm never mean or irritating or showstopping. I also don't stop moving. "Yep, we have to get going. I know, it's a shame. Last time we were out, the dog tried to eat the couch, so we need to go back and make sure everything's still there. I know, dogs are weird. It was lovely to see you. We'll have to get together again soon!" - all the while as I'm moving both of us to the door.