No, the "is the lock necessary" question was the first step in my development of the
Dick O'Kane targeting technique, where I turn the @#$@# PK off, throw target range out the window, sight the TDC at a presently empty spot in the ocean and aim so accurately that I can hit 5 yards aft of the bow crane.
The periscope lock has nothing to do with targeting other than holding the periscope's crosshairs on the middle of the target. For conventional targeting this is a great thing because you're doing so much input all at once.
Also, the PK must be on to show the impact point on the target. With the PK off, you can see the torpedo track on the attack screen but not the impact point. With the Dick O'Kane you never see the "x" on the target and you won't miss it either.
