(The obvious answer to this inconsistency is that they had no reason to spy on their brother/the first-years’ dorm, but… He used to be Percy’s rat. They never spied on Percy? BS.)
Rowling’s handwave was that, due to (iirc) worry over being discovered, they only took out the Map when they needed to scope out areas for their pranks, and then they always focused on the areas in question. They apparently never felt the need to use the Map to actually spy on anyone, and never bothered to look beyond what was needed for a prank. According to Rowling.
What makes you think they didn’t?
(The obvious answer to this inconsistency is that they had no reason to spy on their brother/the first-years’ dorm, but… He used to be Percy’s rat. They never spied on Percy? BS.)
Rowling’s handwave was that, due to (iirc) worry over being discovered, they only took out the Map when they needed to scope out areas for their pranks, and then they always focused on the areas in question. They apparently never felt the need to use the Map to actually spy on anyone, and never bothered to look beyond what was needed for a prank. According to Rowling.