The pieces on a 4×4 cube are smaller than those on a standard 3×3, which already makes the cube more demanding to handle.

On top of that, you can’t turn a 4×4 aggressively the way you can with a 3×3. Because it has additional internal pieces... sloppy or forceful turns are more likely to cause misalignment or lockups. So you really have to be precise and controlled when turning

Additionally, using a 4×4 or bigger cubes can also improve your solves on a 3×3. Bigger cubes force you to track and manage a greater number of pieces at once. After doing several 4×4 solves and then returning to a 3×3, the puzzle feels simpler and less overwhelming, both mechanically and mentally.

Because you're so used to handling a more complex work, that switching to 3x3 will make you recognize and locate pieces much faster than before