Tasks that trigger on a field change (but only once)

It would be super useful to be able to set a triggered task type as either 'daily' or 'daily ( one time only)' much like the way Zapier works.

Example: I have a task to send data to a parser to create an invoice when the status changes to a certain value.

The problem is that it will continue to send the email every day after the value has been changed --creating multiple duplicate invoices.

My work around was to make another field that updates at the same time (sent/not sent) and make the original email send only if that field is (not sent.) I have found this combination of filters to produce a lot of errors. Emails are sent when they are not supposed to be or not sent when they should be.

I wish I could set the task to only trigger once when the value changes like Zapier.

I have the same issue: having to send out a mail when a field hits a certain value, but only once, upon the value change.

As this feature does not exist, I have to introduce additional fields and scheduled tasks, just to create a workaround which is terribly cumbersome and very error prone.