This. Added benefit of sweetspot on flat to rolling roads is you’re going fast enough that you really can feel the benefits of getting more aero. I find it much easier to find the motivation to get and stay aero when I’m hitting a meaningful amount of wind resistance! Same logic unfortunately means I find it almost impossible to do sustained aero position when indoors or when climbing.
I have a nice loop for doing sweetspot and aero training - ~10 miles long, decent road surface, fairly exposed so usually a bit of wind, pretty flat, not much traffic and barring one roundabout where you might have to ease up it’s pretty continuous pedaling. Really notice the difference when I go train that way regularly.