Well, not exactly success, but he figured out both Danny and Jon are falling for each other.
Something more of importance:
- He supported inviting Jon and invited him himself
- it's his plan that they can capture one wight... oh, actually that was kinda success, except both Night King and Cercei actually profited from it. But that helped to hook up Jon and Danny :)
So actually nothing except for romance which makes him now even more worried than before :D
Edit: actually when I think about it, he did have a part in one success. The fact that he attacked Castelry Rock and that Jamie anticipated that, resulted in joined forces of Lannisters and other lords marching on Highgarden. And that is a bit of success afterwards, since they were out in the open so Danny can use dragon and Dothrakies. Since everyone including Jon advices her against dragonfire in the cities, this created oportunity to demonstrate power and dragon. Now lords are terrified and soldiers bent the knee, which was far more effective than having few more thousands of soldiers from Highgarden. Lords of the Reach sided with Cercei anyway, so although they lost Highgarden and allies, they delievered the punch that more or less would won the war for them IF they had time to continue.
So, being clever caused Jamie to be more clever and made dragon attack possible without civilian victims.
But willingly and planning military strategies, I guess he was a big failure this season.