You rather get a quick KO believe me...The chances of long term trauma are much much less...Unless the KO is sincerely brutal...I mean BRUTAL...not 1 punch or a combo then out....The worst possibility is a bleed...Also if that happens it is easier for the Doctors to perform emergency surgery...

If it is over a long duration the brain not only takes little bits of trauma at a time but the brain has time to swell up as well the pressure on the skull is your biggest enemy...Doctors can not operate and a possibility the CT can miss the exact trouble sport until the swelling goes down....

Neither is recommended of course but you rather not take all the abuse as the long term beatings are what leads to being punch drunk