Maintaining a browser support policy
Your browser support policy is a living document and it will change over time, for example: as new browsers are adopted by your users; as code libraries are updated on your site; or, as the site is redesigned.
I suggest reviewing your browser support policy on a quarterly basis, regardless of the type or size of Web site. Not every quarterly review will result in changes to the policy, but it will give you insight into the current state of the browser space, as it relates to your site. In short, it will make you a better informed Web professional.
The quarterly review process is much the same as the process you followed to establish your browser support policy – only, with all of the proper tools in place, the data should be easier to obtain, and updating the policy will go more quickly. Once the policy has been updated, be sure to communicate the changes and update any user-facing messaging.