The weird thing about the Borg is that they virtually always let the first attack succeed - even when it is by an already definitely
known method, such as a Starfleet hand phaser. They only adapt to the second attack, and that adaptation is successful regardless of the method.
There are one or two exceptions to that. In "Q Who?", the Borg don't allow even the first photon torpedo to succeed, say. But such things are extremely rare.
We might well deduce that the Borg not only don't mind losing a few Drones or a few cubic meters of their Cube to an attack - they want
to be defeated that way. After all, such losses don't really cost them anything; VOY even implies that Drone souls are immortal and collectively stored, and Drone bodies thus are truly expendable even in the personal opinion of the body's former owner if anybody bothered to ask. Being lost to an enemy weapon is a victory for the Borg, as they will have learned new things about not just the weapon but the current tactics of the enemy.
The Collective can't afford to do that with photon torpedoes, though, because a single unopposed shot would vaporize their entire ship and preclude learning. So they let hand phaser shots and tommy-gun bullets get through, but not torpedoes.