A caution: the Last Edited Date is not always reliable. It's possible to change a person without changing the Last Edited Date, and it's possible to change a Last Edited Date without changing the person. I've never been able to pin down all the possible causes of this problem, but such causes exist.I suspect that for most RM users most of the time, the Last Edited Date is fairly reliable and it will probably meet your needs.
Curiously, the relatively new TreeShare feature, of all things, offered some significant promise in this area. In order to work properly, TreeShare needs to know with considerable accuracy what has changed and what has not changed. But parts of TreeShare's capability in that regard were disabled shortly after TreeShare was introduced due to TreeShare only having a manual sync capability. For example, suppose you make changes to Places using the Place List. If a person in your database is using a Place that has changed, the person is "changed" even though the person hasn't been edited. The initial release of TreeShare knew about such changes, but TreeShare no longer knows about such changes.
It's a very subtle point, and there is an entirely reasonable argument to be made that you might not want the Last Edited Date to be changed just because of a Place change made through the Place List. Similar issues occur with changes to sources and to media where they can change and the Last Edited Date doesn't change. I could be wrong but it seems to me that the Last Edited Date sometimes doesn't change when I make source or media changes, even when those changes are made through the Edit Person screen. The Last Edited Date certainly doesn't change if you make source changes through Lists>Source List or if you make media changes through Lists>Media Gallery or if you make media changes through tagging.
The flip side is that the Last Edited Date will change if you edit a note only to look at it and exit with OK and without changing the note. But if you cancel out of a note to avoid changing the Last Edited Date and if it turns out that you actually did change the note, your change to the note will be lost without warning.