Just in the last week I've heard of two skiers who crashed and injured themselves on what they'd decided was to be the last run. I left an ACL in New Zealand similarly. I believe that deciding it's going to be the last run has an effect that predisposes to a fall. Feel free to speculate as to why. It may be that the decision shifts part of your attention elsewhere. Couple that with tiredness and the more difficult conditions that often apply later in the day and .... So the implication is: decide at the bottom.