Maybe for offshore sailors.
I have no statistics. However, if you are correct casualties would be evenly distributed across the time in combat.
I just don't think that's true for the more "intimate" forms. Might be. Doubt it. And I know attitudes change over time. Not discipline, but attitudes. Resignation moves more short-timers feet than enthusiasm, but still moves them.
And it's well-known but maybe untrue that pilots survival rates increase with experience and time. Maybe that's a function of becoming more familiar with their planes, though, not having to stop and think so much.
Arf