Reasoning for speed and recovery builds are to engage and disengage targets swiftly. Strafing battles are often made easier, time to reach heavy and points of interest are cut down, and running that in tandem with lightweight or agility boosting effects make you a slippery killer. Downside you feel the pain from thorn, burning lock nades, and heavy splash damage. Still, if you get away you can recover way fast then bring the pain again