Feature summary (what you would like to be able to do and where):
A setting to enable the user to hide (or show) the timestamps on the left
There could also be a setting to instead have one header per day but that would be a separate issue and slightly more difficult to implement than making the timestamps removable.
Use case(s) (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):
Here is a comparison between the Wikipedia Watchlist enhanced with a button, "since last seen", via a gadget and the Global Watchlist to illustrate the usefulness and how the problem was discovered:
| GlobalWatchlist | Added button |
 |  |
 | < this screenshot makes it clearer (the panel being visible in the middle of the page was a bug of the Firefox screenshot-taker, it wasn't actually visible there. It shows the configured settings so it may be useful.) |
Users may want to remove or be able to remove the timestamps to make the watchlist less cluttered, easier to glance over, clearer and more minimal. Always on the utmost left there would be the title of the page in an organized, well-looking way. Users may want to adjust the watchlist to look more like the Wikipedia Watchlist they're used to which doesn't have these timestamps but a header per day.
Benefits (why should this be implemented?):
The Watchlist displays lots of info and in the future even more info could be added to it. Some may want to keep it minimal and the timestamps can clutter the watchlist, often without any clear benefit. It would be useful if there was a setting to have the timestamps hidden.