The recent report on diversity also spoke to term limits. 21% of public companies in Canada have term limits. The reason that term limits came up in the diversity report is that as directors leave the board, the hope is that their replacements are a more diverse group. In general, if a board has had the same group of people for the past 20 years, odds are that the group is mostly older white guys. This is an extreme example.
Most boards turn over more frequently than every 20 years. When you are trying to improve diversity on your board, term limits will play a role. Best practices has suggested that a board member should serve no longer than 3 terms of three years each. When you turn your board over more frequently, you have a better chance of improving diversity.