Strictly speaking you don't even have to land with diversion fuel. The requirement once airborne is to land with more than the half hour final reserve. Once it is clear that you may arrive at destination without the fuel necessary to reach your alternate you make a 'decision' as to whether to divert or commit to your destination so as to land with more than final reserve.
Obviously an individial pilot's own 'airmanship' would dictate what they decide to do, and I've seen both ends of the spectrum there!
Me? I like plenty of gas - but some don't seem so bothered...