If you need to transition from a close shot to a long shot. The rear sight is already up.
Secondly; You are going to laugh at this! Watch how many guys forget to turn those things ON!
Much less, turn them OFF!
You have to TRAIN with the optics...TRAIN! I still saw guys who were not familiar with the optics, install them because it looked cool. Close one-eye when engaging targets at close range...WTF?