Will adding an instruction in my assessments to tell students that do not follow instructions that they need to follow instructions make them suddenly do so ?

The dilemma of trying to give feedback before an assessment is marked. So often we write “please check before submission that all the requested information is included and that you have met the marking criteria” in the comments that I wonder whether to make this it part of the initial question. My gut feeling is that it will not make a jot of difference, but it will allow makers to cut and paste something neatly from the unit outline …