What is the most efficient approach if you have to physical restrain someone in case of a punch-up you want to break up?

Basket hold is most effective if you can do it.

it's a techinque taught when I use to work with emotionally disturbed (psychotic) teens.

You have to come up behind them, grab one wrist, and wrap it around their body, and then get the other wrist and do the same. Then buckle their knees from behind, and bring them down to a sitting position and do not let go of their wrists. Very effective.......and hard for them to break loose. You can hold them indefinitely like that.

However in a Street fight situation.........perhaps the double under the arm head lock is best. Again, come up from behind, hook your arms under theirs and intertwine your fingers behind their neck.

Be aware, the easiest way to break that hold, is for them to simply go limp and just drop down, using their weight............but often in a fight, with adrenaline flowing.....they'll struggle rather then just go limp.

With the basket hold , even going limp doesn't help them. The hold still works.