Although research on adaptive systems has begun only recently, studies have shown the benefits of using adaptive systems. However most of those studies have examined systems with and without adaptive qualities, disregarding additional factors that may influence the interaction. This study presents a first step towards a more comprehensive evaluation of adaptive systems. We assert that adaptive systems should be examined with regard to different types of tasks, different situations and using various users to be able to determine the conditions in which adaptivity will be beneficial. A preliminary study evaluated adaptivity when performing routine and infrequent tasks. The study showed that adaptivity is beneficial for routine tasks, and that adaptivity impairs performance of infrequent tasks. The study proposes a method to calculate the point at which adaptivity ceases to be beneficial as a function of the relative frequencies of different tasks and provides a starting point for a more comprehensive understanding of the subject.