if resting was so important, i'd do 100000 sets in one day then take the whole month off and be the biggest guy on earth.
can be said both ways.
trials and errors. for me personally i prefer extremely high frequency. sometimes i train the same muscles twice in one day. no that's not a typo. the way i see it is, if i can go into the gym and lift at 100% strength, then i'm going. like Shawn Ray said, there is no such thing as over training, only under-recuperation.