Spell Completion
This is the activation method for scrolls. A scroll is a spell that is mostly finished. The preparation is done for the caster, so no preparation time is needed beforehand as with normal spellcasting. All that’s left to do is perform the finishing parts of the spellcasting (the final gestures, words, and so on). To use a spell completion item safely, a character must be of high enough level in the right class to cast the spell already. If he can’t already cast the spell, there’s a chance he’ll make a mistake. Activating a spell completion item is a standard action and provokes attacks of opportunity exactly as casting a spell does.
Drinking a potion, reading a scroll, or casting a spell using a wand or a staff all take a standard action, no matter what the casting time of the spell would be normally. (Good for long casting time spells, like lesser restoration; bad for short casting time spell, like feather fall).
What the DMG says is that activating an item like a wand either takes the spell's base casting time, or 1 standard action, whichever is longer.
USING ITEMS
To use a magic item, it must be activated, although sometimes activation simply means putting a ring on your finger. Some items, once donned, function constantly. In most cases, using an item requires a standard action that does not provoke attacks of opportunity. By contrast, spell completion items are treated like spells in combat and do provoke attacks of opportunity.
Activating a magic item is a standard action unless the item description indicates otherwise. However, the casting time of a spell is the time required to activate the same power in an item, regardless of the type of magic item, unless the item description specifically states otherwise.
they should change it to 'activating the item takes a standard action or the normal casting time, whichever is shorter' and then use the duration modifier on the cost of the item.