People also forget that some of those deaths were probably to old age. Think about that for a minute: Assuming he eventually figured out how not to die of hunger or thirst, just how many times do you think he spent FIFTY YEARS (or more!) of subjective time practicingWe have NO context of how long the loop actually went on before Dormammu relented, so for all we know Doctor Strange was constantly fighting and dying to Dormammu for months, or even years. Every time the loop happened he used different abilities and strategies, and though he lost every time, he still got better and better at his magical talents.
So many people seem to forget this.
—Patrick