We have been using Scrum for some time now. We have multiple development team following Scrum, and we try to implement Scrum as suggested by the official Scrum guide. One of the practises followed by the management is to employ a part time Scrum Master who overlooks Scrum implementation. As per my knowledge, each team should have its own Scrum Master. Is this true? Is it advisable to have a single SM overlook multiple teams?