Probably that's why they don't break under the strain of their incredible adventures. ('Yes, it isn't always fun to one week slowly be de-evolving, the next week transported back into time accidentally, the week after that meeting some aliens with a really nasty or at least weird culture, then to suffer one week later from a transporter cloning accident, only to be possessed by a disembodied alien intelligence in the fifth week, but hey! those 40 minute highlights still make up for our otherwise extremely boring existence!')