When the "sneak" (crouch) button is held, the Rapid Use System does not work for any interaction, especially the Constant Placing System (seen in MCPE-51825).
Steps to Reproduce (in Creative mode)
Obtain a block that is not part of the Constant Placing System (walls, doors, or plants can be used here)
Fly upwards a few blocks (make sure you can still target the blocks below you)
Then do the following:
Fly forwards while sprinting
Hold the "jump" and "sneak" buttons
Look down
Hold the "use" with the block from earlier in hand
Here, the block is only placed every 0.25 seconds. If the "jump" and "sneak" step above were removed, the block would be placed rapidly.
Comments 5
Also, the doors are placing slowly because of MCPE-90558. When interacting with most blocks, the Rapid Use System is disabled, meaning that the game relies on the standard interaction timer of 0.25 seconds.
For me, the doors seem to place equally slow (about every 3 blocks) when attempting to place a line of them while both holding fly and crouch at the same time and just sprinting alone. Are you able to reproduce this issue in the latest beta?