I can’t help with the middle days but I have a trick for Friday. Look for something the entire week that can be pushed, for a semi valid reason, to Friday afternoon/evening. Preferably something that’s easy but takes a lot of waiting. That way when someone tries to drop some shit on you last minute you can say " sorry boss I’m already scheduled for x or y priority task, it’ll have to wait until Monday " it doesn’t always work, especially if your boss is a fucking Slave Driver. But it has saved me a few times.

Right now I have a ticket scheduled for around 3:30 that should keep me “busy” until 5.

This is why I only work 32h and take Fridays off.