I'm with Ken on the volume stuff being mental and quite difficult to quantify... I mean rest time between reps can make diff.. When is rest not considered within the set? 5x10 empty bar wears my fat butt out.
True, rest between sets is a big factor. That's why BB training is so exhausting for me (maybe I should lower the percentages when training BB style). "Rest", or holding the weight, between reps is also a big one, but for most cases it's assumed that you don't "take your time" between reps.
I think people will naturally know their own basic guidelines provided that they know and train their 1RM.