That was the problem in 2e. People talk about interupting casters, but, that was incredibly difficult to do in 2e. Your initiative was modified by the casting time of the spell, typically 1-3. A medium creature started at a +3 mod for initiative. The wizard beat the monster almost every time. A large monster was +6. Let's each roll d10's. I roll a d10+1- my Dex bonus, you roll a d10 +6 . Guess who wins pretty much every time?
The whole, "Oh, well casters lost their spells all the time" thing is such an overblown myth of early edition play. Never minding any reasonably tactically minded group had the casters in the back line where they simply couldn't be attacked at all most of the time. That was the point. You lined up your three fighters and the cleric on the front line, the rogue and whatever sixth character you had was in the next line and the wizard was in the back safe as banks. Virtually no monsters had ranged attacks and, as soon as the fighters engaged in melee, even those that did have ranged attacks could no long use them.
I've never understood this myth of wizards always losing spells. Sure, it happened once in a blue moon, but, otherwise? It almost never happened.