During the rut, as much time as you can spare, you need to be in the woods. I don't care what time of day you can get there, you just need to get there. One important note, if you're in your stand and watch a buck chase a doe say 100, 200 yards away, get down as quietly as possible and move over to that area. Chances are, you will see more bucks running the same line and if you don't move, you will be watching them too from a far. Any noise/disturbance you make will be minimal.