This was a question posed by one of my players, and I had never really considered it, but may also explain why over the years my players have rarely used the detection spells except out of combat.
Both RM2 and RMSS define the spells basically the same way. It doesn't matter what your detecting, from Essence magic to Invisibility, you have to Spend a whole round Concentrating in order to "see" the thing being detected.
Now, I suppose it isn't much of an Issue for the magic Detection spells, But this Makes Detecting Invisibility rather useless. A Immobile invisible object may eventual be detected, after an amount of time spent looking from one area to the next, but for a mobile foe, Unless you have some Idea where they are, and they don't move, you may never actually "See" the invisible foe. (I understand that even if you do see them, you aren't removing the invisibility, just creating, perhaps, some sort of Blur or aura about the area where they are. Which is why you get a penalty to attack them still)
And perhaps that is fine for lower level spells, But there is never a More powerful version that allows a better ability to detect. Just seems off.
How have other GMs felt about this, and how would you feel about adding higher level Detection spells that are more "efficient"?
As an Aside, Since all of the detection spells for magic are defined by realm, why are not magic Items each given a Realm definition?