The thing about terminal E is that all the gates are shared. Delta (or any other airline) doesn't have exclusive access to a gate. Often, flights do end up at the same gate, day after day, but not always.

I don't know what will happen with gate sharing in E after the 4 new gates open.

I did walk from the far side of terminal B to the far side of terminal E. It took like 18 minutes at an extremely rapid pace. It was fun! I wish there were an A <-> B airside connection.