With the knowledge that you have supporting players arriving close behind you, the decision to blow over the ball can be decisive. The second supporting player can assess the situation and shout “Blow” to let the first supporting player know that they can eliminate a threat and feel safe that possession will be retained.
Once you’ve identified a threat to eliminate, your job is to take them out of the game. Not permanently (we’re not animals!) but for at least one phase of play. Ideally, you want to put the threat on their back and get up off of them. If you identify a threat at the breakdown, they need to be incapacitated so that there’s no chance of them making a covering tackle or competing at the next breakdown.