Out of the three types of tests listed on the Treejack website, Tree Testing Card sorting, and first click testing, the type I would use for my mobile app is card sorting because I would like to focus on optimizing the sites pages so users can interact with them as fluid and seamlessly as possible to create a painless, easy, and fast paced experience. To counteract the slow nature of their pre flight preparation,  the results of how fast a user finds a particular part of the site and where they are getting stuck would be especially helpful to me in creating this kind of experience because with that information I would know exactly what parts of each page  needed to be either put further up or further down in the information architecture, and with each iteration, I would achieve a slightly faster time for user interaction.