Hello Emilio!
It's nice to hear from you again! 🥳
I agree with you balance is the key! Ok, so let's cover your question
Yes, it is possible to do it!
But first things first, you need to ensure with the company in which Time Off Type you want to apply this Policy. (Remember that a company can have too many Time Off Types depending on how they manage their Employee's Time Offs)
I will give you an example of how it works and how to configure it:
Step 1:
Activate "Count of Extra Hours" in Attendance App > Settings.

Note: Here you need to set up when Odoo needs to start counting the extra hours, (this is crucial) and define the Tolerances in favor of the Company and of the Employee.
Step 2:
In this case, to address your doubts, I created a new Time Off Type called Extra Hours. The key factor determining whether the extra hours can be taken or not is the 'Deduct extra hours' field. This field needs to be enabled.

Now, let's see how what we just configured works:
Let's say the policy came into effect on January 1st, 2024 (as we have it in the image in step 1), and Mitchell Admin has accumulated 8 extra hours from January 1st until today:

Now, Mitchell Admin wants to use those hours to take a break. In this case, Mitchell has to request a Time Off by selecting the Time Off Type 'Extra Hours'

If we notice, Odoo will help Mitchell Admin know how many extra hours he has accumulated or available to use, and it will highlight them in green. In case, he doesn't have enough, Odoo won't allow requesting these hours because they haven't been accumulated or assigned by Human Resources.
Example: If he requests more than 8 hours:

Resultado:

Depending on the case and company policies, the employee may proceed or follow other processes to take a day off.
I hope my response has been helpful, and remember that it is very important to consider the company's policies when implementing Human Resources processes. 🥳