I think you can get creative using scheduled metric-to-metric imports. Here’s one idea:
1. Create a duplicate input metric ‘Previous Value of Project’
2. Set up a metric-to-metric import from the real ‘Project’ metric into the ‘Previous Value of Project’ metric
3. Schedule that import to run at 7:00am daily (or more frequently)
4. Feed these two metrics into your ‘Change in Project?’ triggering metric, which now resets back to blank/false at 7:00am daily

But if the project value has been changed twice/thrice within an hour on the same day,

‘Previous Value of Project’ remains as it is on that day, due to which notification will not trigger

You could set up 6 identical metric-to-metric P2P imports, and schedule each of those imports to run the maximum 4x per day, so you can cover 24 hours. Perhaps hourly notifications would suffice (vs. potentially getting spammed with 5 real-time notifications within the same hour while a user was testing overrides).

You could also consider expanding on the P2P import setup, such that the final metric is also a result of a P2P import, which users manually trigger with the click of a button on a dashboard. ie, the instructions for users could be Step 1: input your change in the table. Step 2: click the first button (runs the P2P import into the ‘Previous Value of Project’). Step 3: click the next button (runs the P2P import into the ‘Final Value of Project’). Multiple ways to get creative with P2P imports