Measuring/positioning elements improperly includes shadow/effects
It used to be that when you selected an object/element with a drop-shadow (or other effect), the measurements did NOT include the drop-shadow. HOWEVER, now they do and it's causing me lose-my-mind!!! To measure and or position ANYTHING correctly, you have to first turn-off the shadow (in the Appearance panel) then position/measure and THEN turn-on the drop-shadow!!! Seriously, this is an enormous time-waster. PLEASE, allow us to turn off the function where everything is measured-and-positioned by it's drop-shadow. PLEASE
Preferences > General: Use Preview Bounds.