Shas has created the most recent coalition crisis over the words of the director of Channel 10. Shas wants him fired for what he said about Deri and Shas voters. When Netanyahu did not immediately fire him (and I do not know that Netanyahu has the ability to), Shas said they will not participate in Knesset sessions until he is fired.

One day later, and at the last minute Shas ran back in to the Knesset to vote so a law proposed by the Opposition would not pass.

It might have been important and they might have felt it necessary, but their threat is really worthless if they are not willing to carry it out. They didn't even last one day.