The cross choke from mount is one of those submissions that you learn on day one of starting jiu jitsu but can take forever to get good at. It’s not a surprise attack. There are very few tricks to it. Most of the technique’s effectiveness (as far as I understand) is about controlling the position.
I love this submission, not because I’m good at it, but because I believe that maybe I will be good at it one day. I’ve been working at it slowly but steadily. Here’s Roger showing the basics of it:
And here’s one of his black belts breaking it down in more detail:
Like many basic but effective techniques, the cross choke from mount has just a small number of details. It seems that mastering those details requires thousands of reps that develop the right strength, balance, flexibility, and control.