I know that this would seem obvious to some, but to others it may not, and I thought I would help save time for players creating threads about what they think could be a potential “bug”.
If you are looking to speed through the Halo: Combat Evolved Anniversary and Halo 2: Anniversary with the bandanna skull on to complete the challenges then you would be wasting your time. Just like with the par score and time achievements, the challenge requirements will not be met.