It depends on your own unique business strategy! And remember, you can modify the events that you receive alerts for anytime.
Typically it makes sense to monitor your main competitors listings for adjustments like:
Price, Status, Reviews, and various copy adjustments (Title, Bullets, Description, Backend Keywords). It’s always insightful to understand when your competitors are running promotions, out of stock, or receiving feedback from customers. Additionally, it's important to pay attention to your competition’s listing copy so that you better understand the tone of voice, and potential keyword optimizations that they may be utilizing to drive more traffic to their listing.
Alternatively, we recommend that you track your own product listings for things like:
Status, Rating, Ratings, Reviews, Dimension, Weight, Number of Sellers, and Category. Tracking these events ensures that you receive alerts if there are any unforeseen changes made to your listing. Not only will you be the first to know when you receive feedback from customers, you’ll also be alerted if Amazon makes any important changes to your listing as well.
When in doubt, just track all events.
For more information on the various events you can track inside Product Pulse you can read more HERE.