Observers triggered by redstone has inconsistent timing

Phone : Huawei P9

The redstone delay from an a piece of restone activating till an observer outputs power varies to such a large degree that timing sensitive redstone cuircuits are currently not possible.

Test world attached with 2 rows of 6 double piston extenders - one using redstone ontop of observers to trigger the top piston (A) and one triggering it directly with redstone ontop of the piston (B)

B works every time
A works randomly

Video illustrating issue:
https://youtu.be/etqt07lbPGI

In the test world delete retracted bookshelves and place new ones infront of the haybales to reset ( reset cuircuit is not included to keep the restone to the bare bug )