RE: How important is it to know....
Yes what you say makes sense. But I like to know through scouting, trail cams, drive throughs, local reports from land owners etc. What is out there. If you know you have say 5 100" 8 Points and your goals are a 125" then you are just hoping one wanders through. (which can easily happen during the pre-rut and rut). But you may not wish to wait on happen-stance and change areas.
Or suppose those 5 100" 8 points are good deer in your area..do you want to shoot that 80" 6 point? It all depends on your own personal goals.