TLDR; You will probably never have to press this button, but it's there if you want or need to press a button.
Important Note
Rosters and Results already stay in sync automatically
Why Does This Exist?
One strategy we use to we ensure that our Microsite Results can handle the rush of Race-Day traffic is by using a view-only copy of data for participants. This separation of data ensures that a bot or a sudden spike in traffic won't negatively impact your Admin user experience.
By no means is this is an uncommon design paradigm, but it does introduce the extremely rare possibility that the public-facing Results may not perfectly reflect what you see in Admin.
When Should I Press This button?
If you see an issue where an Athlete has stale information, or is missing a Bracket Rank, it might be worth pressing this button. It's relatively harmless and might save you a support call (this is the button they press ). The button kicks off a background Job and depending on the size of your Race could take a minute or two to fully complete.
Example of a good time to Manually Sync Rosters