yes there is a point to going on all three days,
friday- spend the day wandering around the paddocks getting close to all the cars and drivers and taking great pictures.
saturday- watch the action from a lower part of the hill
sunday- watch the action from the best viewing spot on the banking just above molecombe corner
my top tip is get there very early, i tend to be there just as the gates open, time to get a nice breakfast, wander round stuff before the crowds arrive and pick out a prime viewing spot.
another reason for going on more than one day is to hedge your bets weather wise, one year me and the better half got there early, sat in my usual spot huddled under a brolly get absolutely soaked, very miserable, but by the end of the day i had sunburn on the back of my neck