The Last Modified feature is the best thing that has happened to airtable in the past year, no doubt about it. It does work well, but I believe it needs a few more things to get the most out of it.
For example, I would like to introduce a “Lock” feature. The way this would work is that the last modified date value would get locked when a certain value has been added to a field. Example:
The status column has “To Do”, “Doing”, "Done values. We set the Last modified formula to lock whenever the status has the value “Doing”. So when the status has changed from “To Do” to “Doing” the last modified date will be added to the formula field. Now, whenever we change the status from “Doing” to “Done” the last modified date will stay the same or will get locked. So whatever value is then changed to the status field, the last modified date will stay the same.
Basically, this is a needed feature for any formula type of field. Users should be able to lock the calculated value based on some simple criteria which can be defined in the formula.