A team will always be better off with a dedicated, full time scrum master. A scrum master’s role is not about managing the Team. However, don’t fall into the trap of thinking that a scrum master is just about facilitating ceremonies. New teams in particular need a lot of training, mentoring and coaching to get to grips with the art of Scrum. This is without a doubt a full-time job.
Companies should ask themselves if they could afford not to embrace the core agile value of “Focus” by diluting a scrum master’s focus with more than one team? One scrum master, one team is the best way to ensure that an inexperienced team becomes a high functioning agile team as quickly as possible. A high functioning scrum team’s output is bigger than the sum of its parts.
Once a team has moved through the storming, forming, norming into the performing phase, and depending on the organisation’s agile maturity, a scrum master can consider taking on another high performing team. High performing teams won’t need as much mentoring as an inexperienced team and a scrum master’s role would be more about facilitating and unblocking the team.
You won’t kill two birds with one stone by assigning more than one scrum team per scrum master. It would rather be a case of chasing two rabbits and catching neither.