Why am I surprised my dog actually made the connection?

I always heard that you can’t teach on old dog new tricks, but I think I have done just that. I have a spaniel mix named Dutchess. She’s about 7 years old. As far as dogs go, she’s fine. I like her. Except when she gets to barking. When she gets to barking she’s just apeshit and it drives me insane. In fact, that was one of the first questions I asked here….how to stop my dog from barking.
She’ll be sitting at the front door, watching the world go by, then see something that sets her off and she’ll go nuts. The screaming in the house is unbearable so I’ll open the back door and she’ll fly around the back yard, screaming at the top of her lungs.
Then she’ll come back in and act like nothing happened.

About two weeks ago I laid down the law. When she goes off on her rant, she is not allowed back in the house for at least the next 30 minutes. The hardest part of this was my husband. She’ll sit at the back door and whine and bark and yelp and it is so tempting to give in and let her in just to shut her up. To me, it’s like giving in to a kid having a temper tantrum, and that is the worst thing you can do! I can ignore the behavior, but him, not so much. He gets all tense and angry.
Anyway, I finally convinced him to give this a try…and I’ll be danged if it isn’t working. She’ll sit at the back door, asking to come in, and I make a point of letting her know that I am flat ignoring her! Eventually she’ll just lay down, resigned. The barking fits have decreased from about 5 a day, down to 1 a day, and I am expecting even that to go away.