Most shows we only use 2. One is for the layout (3 tracks), the other is strictly for programming with tether only. Bigger layouts may have 2 for running mainlines, 2 or more programming/yard, and the one I use to run my timesaver puzzle. The Trackers do not block wire layouts, we usually don't have enough time to set something like that up. Each loop/circuit of track gets its own TIU output That's it.
Steve