I thought about this a bit more, while I was away from my desk for a bit... ? . There might be a minor case for coasting, but probably not enough to let it bother you unless you're really pushing for hypermiling marginal gains.
Say you're driving into a biggish dip on a big road. There's a classic on the A14 east of the M6... So it's a big downhill, that curves into a climb, back to around the level you started.
In an ICE, you'd ease off the accelerator as gravity starts to speed you up, and you'd end up with your foot off the gas, congratulating yourself on using only enough fuel to idle the engine. Maybe gravity gets you going so fast that you're forced to brake, and you're annoyed because you've wasted some free energy, and worn your brake pad a bit. Perhaps you allow yourself to exceed the speed limit, just to make the most of this free energy, and save your brake pads.
Then as you go into the climb, you've still got momentum, which carries you some way up the hill, so you have to press the accelerator in gradually, later than if you'd started motionless at the bottom.
Now, in an EV that's all different. You can keep your foot in the same position all the way (though they might have coded it differently, to feel more familiar, and it'll depend on settings). As you go down the slope, the software will noticed that it's speeding up, and automatically deliver less power to the motors. Then if gravity makes you exceed the target speed, it'll apply regen, and suck some that energy back into the battery.
When you ascend again, momentum will still carry you some way up the slope, the software will deliver power as that momentum runs out, and keep you going the same speed -- and a lot of that energy will be the energy it harvested from regen on the way down.
BUT. Regen is only about 65% efficient. Maybe if you watch the power meter and try and keep it on zero - that is, genuinely coasting - then use that momentum for the upward slope ahead, that's more efficient. It probably involves breaking the speed limit, same as in an ICE.
For me, it's interesting from an academic point of view, but I don't think it'll make enough difference to make it worth the effort on my own journeys.
Of course going slower up hills always saves fuel. The question is, does regen mean going slower down hills saves fuel? Or is it more efficient to turn that energy into momentum than into electrons?