Most E fares I see are unseated when I open a gate. Sometimes, they have seats. It leads me to believe that the savvy people pick a seat assignment before checking in.

As with any fare, if a non-status passenger doesn't choose a seat assignment before checking in and all that's left are preferred, exit rows, or C+, then they're added to the airport standby list and only the gate agent for that flight will be able to assign the seat.