Think of it like a high school physics problem. When you’re up in the mountains, you have a lot of potential energy. You want to turn that into kinetic energy. The question is: later or now?

If you want it later, you can capture the energy in the battery (regen). But charging and discharging are not 100% efficient, so you lose some of it along the way.

Using it now by converting directly to kinetic energy (coasting) avoids that. So in theory, it’s superior. But in practice, you probably can’t gain speed forever (speed limits and traffic and safety and all that).

So I’d coast as much as possible, using regen only when necessary to adjust speed for the conditions.