Throughout playing 3.0e/3.5e for years, and especially from playing later official campaign modules such as Red Hand of Doom, both players and the DMs in my play group have now realized that in almost all of the important combats, both villains and PCs are buffing them up to the most. So, many combats are like dispelling contest. Not using dispel magic (or greater version, etc.) on spellcasters or their allies is, a bad decision. To kill a buffed opponents (or PCs), ones must first dispel and debuff the foes, or their attacks (both melee/ranged ones and spells) never reach to the target, or worse, they can't go close to them.
Now, many fiends can use Greater Dispel Magic at will as SP ability. And sorcerers with Dispelling spells in their spells known are far more popular than wizards in official modules. So I guess persistent spell build never shines in a playgroup with similar experience and doctrines.