Whenever we need to use Synchronize with Central (SwC) I advocate for using the button for Synchronize and Modify Settings every time.
Doing so allows Revit to present us with the Synchronize with Central dialog.
I encourage everyone to take a moment and type a brief description in the Comment field provided. What motivated you to use SwC just now? That's the gist of what should be recorded there. I find that people are more receptive to making a habit of it once they see it can prove to be very useful to just about everyone working on the project.
We can review the comments anytime we choose to, even if we don't have a project open yet. That means that anyone who can at least fire up Revit can review project comments even if they don't really need to do any work in Revit.
Yes, the Show History button on Collaborate ribbon is awake even if no project is open. Click Show History, browse to the location of the relevant Central File and click Open. The comments are presented to us like this.
I doubt it is hard to imagine how having everyone on the project team recording comments (time stamp and username are stored automatically too) can be helpful for diagnosing issues, checking the status of tasks, and even a quick review of user activity on a given project file. It will also become obvious who isn't playing along pretty quickly.
I also recommend that we never use the other button for Synchronize Now (that's why I put the red X on it in the image above). It doesn't present the dialog so there is no opportunity to store a comment and equally important is that is does not relinquish User Created worksets automatically.
If you pay close attention you'll notice that all of the other kinds of worksets are automatically checked when the Synchronize and Modify Settings dialog is open. Those other worksets are relinquished with Synchronize Now, not User Created worksets though. If you use Synchronize Now and you've ever been accused of retaining ownership of these worksets...that's likely why.
If it helps:
Green Arrows in Circle SwC = Good!!
Lighting Bolt SwC = Not Good!!
If you're interested in taking a peek at Kinship's features you'll find that these comments can be reviewed at will with just a browser.