Sneaking in the corner above Jarl Balgruuf in Dragonsreach doesn't work?

Basically the title.

I came across a Short that said if you sneak into the corner above the Jarl in Dragonsreach and keep moving around, you can level your Sneak skill rapidly because the NPCs will constantly detect and lose sight of you. It worked for him.

I'm playing Skyrim AE on Nintendo Switch, and I tried it for a while, but it doesn't seem to be working. Have I done something wrong? Is there another good way to level Sneak quickly?