every wednesday, but ill do a different variation every time. pulling heavy from the floor every week is too taxing on your cns and you will start going backwards real quick, unless your a beginner and not that strong yet.
once ATM. i've done max of 2/ wk. it's a personal thing and i feel i'm better off at once a week and changing the rep range every few weeks. i do however throw in one or two of SLDLs/squats (front/back)/good mornings in there as accessory lifts.
eo wk, no reason to go every wk for me, too stressful on my central nervous system, and I've found if I limit them to eo wk I'm even stronger, and my body is no as tore down all wk
If you're deadlifting heavy enough it SHOULD be scheduled before an off day. Even when I've stuck with a routine for months I still can't work out the next day my back is so sore/tired.
I reccomend once every 6 or 7 days and go heavy. 5 sets of 5 reps is good.