Again, though, the defining 40k short story on Kharn shows that even the most Berzerkerish of the Berzerkers (Kharn) thinks in complex terms during battle, and fights as part of a larger tactical plan.
Berzerkers do what they do out of religious zeal and for the pleasure they receive when they kill. They venerate certain actions (killing, gaining skulls for the Skull Throne and blood for the Blood god), and they favor certain ways of carrying out said actions (intense close combat). Even though their mode is more challenging than the conventional means of battle (firearms from a distance) they don't seem to sacrifice common sense when going into battle. They accept the greater danger as part of their calling, but they still act in conjunction with other supporting assets (whose users they probably don't respect, but whatever).
m1acca1551 has it exactly right.