My best advice.. whatever pleases your eye and provides a proper habitat for your fish.
That said, make sure you leave enough room for both your hand, AND your scraper tool to be able to clean off the algae. A magnet scraper will do most of the work, but you WILL need to get hands on with some of it. if you cant get in there with a scraper at an angle where the scraper actually works.. well you can see where i am going here...