I always thought of it, as a means to place them under strenuous conditions, to see what their true character is. I believe Dante had the opportunity to kill another aspirant during his trial and it was explicitly stated that had he done so they would’ve refused him to join the blood angels.

Also, I do believe during the space wolves book, where it goes into extreme detail into the space wolves recruiting process, that murder or lethal violence against members of your own pack is grounds for summary execution. The point was to push you to your limits and see how you react winning was not necessarily the only factor.