I agree with you in a rolling situation. That’s when you should be exploring, discovering, pushing limits and experimenting.
But in a fight situation, I’d tell them to skip a sub because it’s often an illusion. How many times have we seen a striker give up a dominant position to go for an armbar or choke? He goes from a position in which his skillset is most widely available–he can ground and pound, he can abort and make space if the guy begins to escape–to an inferior position because he thought a sub was there that either wasn’t, or that he couldn’t finish. The risk of failure is too great to warrant the potential loss of position.
This is why someone like Khabib excelled the way he did. He never lost sight of his gameplan going in. You didn’t see him falling over from mount in armbar attempts or flopping back for an ankle lock–he didn’t even go to his back when he RNCed Conor. He took the subs that were available to him, but only within a very, very narrow set of parameters. Everything he did served the plan. He never fell in love with his striking (looking at you, Maia); he always used it to set up his takedowns. Everything he did worked in unison toward a specific goal.
It’s when fighters deviate from the gameplan that you start to see problems. Suddenly they’re in uncharted waters–we just spent three months on perfecting your takedown into guard pass into GnP from side control while maintaining top position. And here we are now with you on your back after a failed guillotine attempt. Do we have a sequence for sweeping or getting back to your feet with someone in your guard that you’ve drilled often and hard enough to know it’ll work the majority of the time against world class BJJers and wrestlers? Probably not. So now we’re no longer pursuing the our original goal, we’re just fighting to get back to a neutral area. Our forward progression has stopped.
Guys like Lidell and Crocop are also great examples. Both were very hard to take down and keep down, because they pursued getting back to their feet with the sort of singleminded focus that most opponents just didn’t have an answer for. If they devoted say, 70% of their time and energy to standing back up after being taken down, the guy who only devoted 30% in training to holding them down and 30% to working on random submissions from different positions just wasn’t going to be successful in stopping them. Even more than a contest of strength/skill vs strength/skill, it’s a matter of who can impose the circumstances in which that strength/skill can be fully brought to bear.
For a purely BJJ example, you could see this with Marcelo. His RNC is notoriously lethal. For a time you knew that’s what he was constantly working for and there was very little anyone could do to stop or defend it. His gameplan for it was so consistent, so relentless, and so methodical that you might could bump him down a rung in its progression over the course of a match, but had little hope of actually getting him completely off his ladder.