How would 11 be possible? Sure you could avoid a Dark Forest Temple Spirit, but you'd cover all the other rooms, two of which would house unavoidable Temple Guards.
Okay, let's say the guards are in the Dark Forest, the passage leading up to the King's Storeroom from the Chamber of the Sacred Markers, and the Room of the Ancient Warriors. The artifact could be, say, in the Room of the Secret Password.
Come to think of it again, I take back my comment that it would be possible to 11 without a guard. Nonetheless, it is still possible to ENTER eleven rooms without running into a guard.
You begin by going into the Crypt but change course and take the bottom path to the Tomb of the Headless Kings, complete it's objective, and head into the Jesters' Court. After finishing the Court, you race through the Dark Forest avoiding the guard and bust into the Quicksand Bog. Although it wouldn't be advisable, you could still go diagonally up to the Shrine of the Silver Monkey, then to the Room of the Ancient Warriors where the suit of armor opening the door does not have the guard, and ENTERING the Chamber of the Sacred Markers, but not completing its objective (or the door upwards would open, revealing the guard). You could then go back to the Ancient Warriors, change paths, and go to the King's Storeroom, although after completing its objective, the door below cannot open. Then, just go left three rooms and to the artifact's location. 11 rooms entered before artifact room, no guards.