I am occasionally asked how big a board should be. This of course is a trick question. A smart ass answer would be, ‘big enough to reflect a diversity of opinion, but small enough to keep the meetings to a reasonable length.’
Diversity of thought often follows diversity of people. If everyone on the board is an accountant, then in addition to having boring meetings, you are going to be spending time talking about financial stuff. Accountants see the world in numbers. If you have a board composed entirely of graphic designers then I bet the logo for the organization is in good shape. Now, who else can I offend with a stereotype?
Hopefully you see the point I am trying to make, we need to have different people on the board and we need to have a big enough board that we can get this diversity. We need financial people and legal people and human resources people and technical people, etc. However, a board of 15 or more people can be unwieldy unless the board chair is particularly skilled at keeping the conversation moving. Just the time it takes 15 people to say hello to each other can make a meeting feel long.
The board should consider how many members they need to get the work done in an efficient manner. We are looking for the Goldilocks of board size, not too big and not too small, we want it to be just right.