Submission attempts that have a low success ratio:

[ShanghaiBJJ]

So is it that people roll out? Or is it possible to resist effectively when the attacker tries to extend his hips to finish?

There are just too many ways to escape the move, you can sit back up, roll over your shoulder, roll under the guy, jump over his head...

There are counters to each of those escapes, which make it a great position to sweep as has been stated, or to open the guy up.

But to succeed in finishing it the classic way is difficult as there are so many ways out.

B