Welcome to the Make community!
You can still use a single scenario, but you’ll need to use the Make API (only with paid subscription) via the Make integration “Make an API call” module, to amend/update the scenario’s “interval” only on the last 15 mins of Friday and last 2 hours on Sunday (use a filter).
I have provided examples of how to use the Make “Make an API call” module to update a scenario’s scheduling elsewhere on the forum if you want to go down this route. I think it’s in one of the threads I started. View my profile to find this thread.
Hope this helps! Let me know if there are any further questions or issues.
— @samliew