Got some conflicting information to my question...
I do use chalk and I have stuck with overhand grip because it hasn't failed yet. My guess is that I could probably do 500 for reps right now with an alternate grip, but I am doing SS which means it'll be another month and a half before I ever get to that weight. So, should I switch grips NOW or AFTER I'm unable to perform reps overhand? I've never used a hook grip; if that's better than a mixed grip should I switch next Wednesday when deadlift time comes up again, or gut it out with overhand at 355, see if my grip fails, then switch if in fact I cannot complete the reps?
The ambiguity of answers to my initial question is probably due to my inability to discern the timeline implied.