I believe the plan for this particular use is
a slightly modified USGS 7.5' quad. This event is by terraloco, and I don't speak for terraloco, and here's what I'd say if an event were to be produced by Get Lost!!:
Get Lost!! strives to bring maps of the highest possible quality to its rogaine participants. "Possible" means several things, and one of them is that the events have to sustain themselves financially in order for us to be able to continue to function and to bring you more events. Making a map for an area large enough for a rogaine is a significant financial undertaking, even if there is minimal survey involved and most of the work is cartography that uses off-the-shelf data. Using off-the-shelf maps, as opposed to off-the-shelf data, allows us to bring you an event in an interesting area quickly and to build up a following for future events.