I remember prep being a big thing in Prime. During the LoS/JLI conflict we were constantly probing each other's bases for information. You'd go to their base and attack them, fight a little bit and fall back so you had some IC information about what their powers were. People would hold back some of their powers and deliberately use less than their full strength to conceal information from the other team. (ICly of course; OOCly we all read each others bios and knew.) It was cool.
I never really stopped doing this. And if someone told me I got a bit excessive with it, I wouldn't argue. Some things almost never got used because I never fully disengaged that part of my mind.