Leaving a UR open for a short time after making a correction is useful if there is some communication going between the editor and reporter. It is also useful as a "bookmark" if the editor wants to keep an eye on the area.
Make the change, verify what you can on the live map or a local field trip, and inform the reporter that you believe the problem is solved, wait a bit for the map to update, refresh bookmarks, etc....
And ask the reporter to confirm that the problem is solved... wait for that response, or perhaps 2 weeks if no response, before closing the report.
Yes, Los Angeles is blanketed with URs, most of which have no information and few have useful routing and GPS tracks. Unless there is something obvious in the area, it can be difficult to pin down the issue... if there even is one at all, given that users don't realize that the pin is dropped where they hit "report" and not where the map cursor is or where they are when they hit "Send"... and report-send will generally not provide tracks. The report seems to log the track between activating "Report" and tapping "Send"
I had one closed on me this morning. Another L2 sent the initial request for information to the reporter. The reporter indicated that they would provide more information, and the report sat for another week. I drove to the location, verified the issues, made corrections on the map, and sent a message to the reporter.
I still intend to do more work in that area (new housing development), so the UR is nice to have as a reference pin.
This morning, the editor who originally requested more information closed the report without comment. In fairness, my comment to the reporter did not indicate that I intended to do any further work, but it has only been a couple of days (I drove it and made the adjustments Tuesday, tiles updated on the area yesterday)