In the Last Modified Time formula you can watch for changes in selected fields.
I wish I could also add a condition filter to only watch for changes in the selected field if there is a value match.
I know I can do that via an additional separate field that will have a match-type function and then watch for changes of this field using the last-modified-time field… But it just ads unnecessary fields in Airtable. If Last Modified Time formula can do that, it eliminates need for the extra field.
With number of fields in Airtable limited to 500 fields, saving every field counts.