Four people seems to be an interesting threshold when it comes to groups. The British special forces, for example, started doing four man teams and several unit

Four people seems to be an interesting threshold when it comes to groups. The British special forces, for example, started doing four man teams and several units of other countries followed their example (SEALS, KSK, etc). https://www.sasregiment.org.uk/patrol.html https://www.sasregiment.org.uk/patrol.html