Keep Your Foot on the Pedrogas Achievement in Halo: The Master Chief Collection

This achievement will prove to be one of the most difficult tasks within the entire game. It's worth noting that you may want to grab a cooperative partner when working on this achievement for two reasons: one, the extra firepower will help put down enemies a little quicker; two, one player can usually act as a decent distraction while the second player attempts to push on and run by as many enemies as possible in an attempt to grab the next checkpoint.

As is the case with these achievements, a text-based guide would be too tedious in explaining every single mission within the game, so please refer to THIS LINK, courtesy of Vodred for an in-depth look at completing Halo: Reach's Legendary Campaign in under three hours.

NOTE: By following the speed running tactics provided in the video link above, you will almost certainly obtain the par time achievement for each of the Campaign's nine missions.