I'm betting most people's Gale who dies alot, magic missile is their most cast spell as well.
If they are asleep they can't kill Gale
If they are on the other side of a fog cloud they can't see Gale to kill him
If he has mage armor up and staying at range he is more likely to live than not in average encounters
If there are 4 Gales with mirror image he's very likely to live.
Thing is playing a mage you can do what other people can do, cast damage spells and trade blows with the enemy and wizards who do loose those battles about as much as they win them. Or you can do what no one else can do and make life on the enemy so agonizing they fall prey to your team. On my team Magic Missile is Gale's last resort, he has it in case a teamate leaves an enemy at 1 or 2 HP and there are other monsters still in play, but most of the time, if he's going to use a spell slot at all ( because these cantrips are fire) it's a sleep spell, or a color spray, or a fog cloud, or a mirror image, or a misty step away.
