Short duration tasks for text-independent speaker verification have received relatively little attention when compared to that directed at tasks involving many minutes of speech. In this paper we investigate verification performance on a range of durations from a few seconds to a few minutes. We begin with a state-of-the-art GMM-based system operating on a few minutes of speech per person and show that the same system is suboptimal on short (10 seconds) speech recordings. In particular we highlight that optimal frame selection exhibits a dependency on overall duration. This work sheds some light on the difficulties of transposing recent and important techniques such as SVM-NAP to the short duration tasks.