A longer series is better for a better team: Can you see this at a glance?
It's the "central limit theorem". If a single event has any probability distribution with finite mean, $\mu$, and finite standard distribution, $\sigma$, then the average, over n trials, has approximately a normal distribution with mean $\mu$ and standard distribution $\frac{\sigma}{\sqrt{n}}$. The larger n is, the smaller the standard distribution is. That means that the larger n is the less variation from the mean there is likely to be.