Rickety Scaffolding is an achievement in Run 3.
The Runner is a good character for this achievement because she is easy overall to control. The Lizard is also good for if you miss one you can hit a string above it, and it is also slow and easy to control. Another good character is the Child, as if you would land on a Crumbling tile, it would not dislodge unless you jump off it.
Another option is the Pastafarian, as the bridge never breaks if you keep jumping on it. This removes the need to worry about the crumbling tiles. Just keeping aiming for holes and you should get the achievement.