So I played around with redstone and noticed something strange. I made a simple symmetrical system to show it off.

On the screenshot, I provided all the information needed to reproduce my bug.

There are six levers. The system is totally symmetrical. All four levers on the right cause pistons to extend and retract, but those two levers on the left work strangely.

If I use them very fast they all work as intended. If I press them with a delay of a second they do not cause pistons to retract, even tho those on the right do that without any problems.