RE: Singles for Deadlift
I cant answer about what is best and benefits. But if your form goes off a bit when doing 5 or 6 reps a set, you should do each rep as a single (almost). Set up, lift, lower weight back down, and then take a few seconds to reset grip and stance, then lift again.
This works well for me, allows me to keep my form good. Essentially, this is how you should do it anyway, as the weight should be 'dead' before you lift.