No no no no no. If you are summoning (as opposed to creating) a creature, the summoning will be very short. The control is what sets the effective duration...Unless you, say, summon a troll into the middle of the gatehouse and don't care about controlling it.
Interesting approach.
Right now, I have creation and summoning as the same Intent, but we could seperate them and require that a summoning be followed by a successul binding like in the RPG
Sorcerer. I like that approach.
So creation would make something new, and that something disappears after the duration. Then again, lots of spells do that inherently, e.g. a Fireball already creates fire. Maybe creation is not really an intent, but a means.
But a summoning would bring something that exists elsewhere to your current location... I'll be thinking about it.