Elminster is a perfect example for this thread as he's only at 400k and change in gear, not counting his pipe. For an NPC he's less than half of WBL...as a PC (which he was one of the original characters of Ed Greenwood IIRC) he's at 5% of WBL.
+5 tomes for each stat would eat up almost 90% of his total for an NPC. He's used wish 4 times for his IQ already, so he only needs to cast it one more time.