77Tigers

I know what is happening here. This is 100% about how pending ticks are processed. Suppose we have chunk A which updates before chunk B. Then if a pending tick is processed in chunk A and causes the creating of a pending tick in chunk B, that will then be PROCESSED WITHIN THE SAME GT. This is obviously stupid and the game should just delay these updates to the next gt.

How does this affect observer reliability? Well, whether or not the observer reacts 1rt earlier to an event (and causes randomness) determines on whether or not the update was in a redstoning tick or not. For example, adding a wall into these setups (where applicable) for 1gt delay will act as a sort of NOT gate that flips whether or not it is reliable or not (to be clear, the wall gets updated across a chunk border, not the observer).

what Memttm said is 100% correct. it is easily possible for blocks to be moved at 10bps, if only pistons finishing movement always updated before pistons starting movement.