I personally tend to walk/cover the entire room, from slightly above head height (when standing), to slightly below head height (when seated) and move quietly around the room waving the iOS device slowly, as shown in the video that’s part of the Trueplay wizard.

When using an iPad (or iPhone), I have the mic at the top and hold the right side of the iPad, it’s screen faces me (more or less) as I circle the room in both directions clockwise/anti-clockwise - I also go ‘diagonally’ across the room too, from corner to opposite corner and then a more general move about towards the end, often concentrating in areas where people sit as the tuning finishes.

Note that the video that you watch before actually doing a TruePlay session explains this.