I've never had a problem with any of my clip-based cases for the 1st gen nook or the nook touch.
As for the notion of using all 4 clip points to attach, I think it would probably be unnecessary and might be kind of a pain to attach and detatch. I suspect, in fact, that the extra slots are present so a leftie (or whoever) could flip the case around and have it open the other way, if they want.
In fact, I just tried this out and I kind of like it better than the traditional way. I'm not a leftie for writing, but I do find books more comfortable to hold in my left hand. Hm.