if you get someone's back 3 times with both leg hooks and the over/under and they escape all 3 times, then it's time to sharpen up your attacks from the back, not lobby to change the rules. If Marcelo or Rafa had anyone on the planet's back 3 times he would 10000% finish at least 1 of them, most likely all 3, especially since it's in his opponent's best interest to escape as fast as possible. Look at Tonon vs Karen and Tonon vs Hinger, both matches ended in OT and both ended in submissions.
When preparing for EBI, you must spend ALOT of time polishing your back and spider web strategies AND your back and spider web escapes. THIS IS HUGE.
Remember, all you need to do is finish your opponent one out of 3 times and all that stalling/gaming goes out the door, ONE OUT OF 3 BACK TAKES! :-)