On our Spigot server we have several big automated storage systems. These storage systems can exist of over 1k hoppers. Inside the storage systems and in the surrounding areas, the redstone timings seem to be varibale and unreliable.

In the attatched screenshots there is an example of a double piston extender for which the extention always works, but the retraction only works 50% of the time. Therefor making this piston extender unreliable. This is also one of the several redstone timings issues we have found, but this was the best example as the other ones are more complex.

The redstone from the screenshots comes from this door design on Youtube:
Video: [https://www.youtube.com/watch?v=K7dWw5nA088
]The double piston extender: 1:30 till 3:30