Good answer - also - besides the ergonomic spreads memory keys on the front panel - you can also store channel arrangements in the MonARC itself. Just hold the store button on the lower panel and then touch any of the channel locations in the group to assign that particular channel location as the "memory store" for that ergonomic spread. It's an ingenious way to store nearly unlimited numbers of non-linear track arrangements.
When you press the "recall" button - all of the locations on MonARC that have an ergonomic spread stored lights up with a white bar, so you know every location that you've used to store a spread at a glance.
The four hardware buttons are the places where I store the most often-used arrangements, but I store quite a few spreads on the MonARC as well. It's one of the things I focus on in the videos I'm shooting this week - difficult to describe but once you see it in action you get how fast and easy it is to set up. It will spoil you for any other way of working.
You'll see of the ways to arrange tracks (including a quick drive through the method described in my post) in
Michael Stareau's new video that rolls through the Tango feature highlights.