When making a verticle double piston extender door using fall blocks as shown in image when using delays of 1 tick (top), and between 3 and 5 ticks. The bottom falling block will not be pulled by the top sticky piston, instead it will just fall. Second, due to speed of the top block it will fall inside the bottom block as the lower piston retracts causing one of the falling blocks to place on top of the other. the falling block inside of the stationary block should place itself on top of the solid block.

please fix this, I do not want to have a really slow door and the only alternative is to have half the door be a non falling block in my situation, and i don't want an ugly door.