In the movie, it looks to me like they did go back to BB many times. The SS is different, as it specifies that they did not go back. 
I don't think so, babe.

You can see different mountains and vistas and landscapes and no one looks like Brokeback. That mountain is very different from others because of its shape and we don't see it again in the film after the summer of 63. BBM was Jack's favorite place because of what he lived there when he was 19. Everything was perfect there and then, the time he was really happy. In some fishing trips Jack was happy, especially in the earlier years after the reunion, but in other trips Jack and Ennis had arguments and moments of misery when Ennis shot Jack’s plane out of the sky. Those fishing trips with Ennis were for Jack a constant reminder of what he could never have. That’s why I think he didn’t really like the Tetons or the Big Horns even if he spent years going there with Ennis. Those places were not special for Jack, because, yeah, Jack was happy when he was there with Ennis, but also left every time with a broken heart.
Brokeback was another thing....It was where Jack found love when they both were free and young and he had lots of beautiful dreams. If our boys had spent all those years of fishing trips going to BBM, I don’t think that Jack had still thought that it was his favorite place, because it’d be an image of their loving feelings but also of their fears, doubts, lies, shame and what Jack hated the most: that they had to hide like if their love was a crime.
I believe that they never went back to BBM. Even in the trailer you can read the line “there are places we can never return”. And I understand why they never went to BBM again. They didn’t want to stain the memory of something that was precious and perfect and the most unique metaphor of the paradise.
Just my opinion, babe.
