Corner jumping I think is very effective on kalt, when in sewers you dash then jump facing the tunnel. anyone there cant get a bead on you quick enough and it gives you enough time to assess the situation. Then again if theres an mg or a nade...You're pretty much waste.
Corner jumps are really effective against mgs on certain maps (NOT KALT). On avalanche for instance, in apartments its alot easier to take out an mg if you jump from a blind spot, giving you more chance to shoot because of mgs slow movement (unless your running 20 sensitivity like me >_>) but yeah. its all for the persons desires and wants ^^; one on one battles, the idea behind jumping is surprise and dodging bullets =/ its useful but you cant shoot as much so hope for bad aim ^^;