I pedal 99% of the time. After a hard day working, and I'm nearly home, I'll sometimes motor in the last mile or so. On the way to work, I'll motor some toward the end of the ride, or pedal lazy, so I don't arrive winded.
I try to set a speed, and pedal up 1 to 2 mph more on the flats. Just pedaling enough to get the heart going, but not enough to get winded most of the time. On the big hill going home, I'll pedal hard for 5 minuites, or not if I feel tired. Even when I did a lot of faux pedaling before I had a bigger gear on the crank, I could still feel a lot of benefit. My strength and wind improved so much from riding the ebike that I now do a lot of riding up steep trails on a bike with no motor. Pedaling to add speed definitely increases range, but the best range is had from simply slowing down. 12 mph will get you double the range of 25 mph.
I never tested range without any peadling, but I suspect adding 2 mph to your speed by pedaling is good for about 25% better range at least. My butt would not stand for 20 or more miles without pedaling. After a few miles no pedaling, my legs fall asleep. When I do a "range test" of my pingbattery, I pedal, but it's faux pedaling that doesn't do too much to add range or speed. I don't like people reporting that they get such and such range, when they pedal like hell all the way, or don't use the motor for some of it. I try to report a range anybody my weight and out of shape could get when I talk about how far my battery can go.
As for pedaling up to speed, it definitely helps. Sometimes I take the downtown route for shopping reasons. A stop sign every block for miles kills my range unless I pedal a lot more on the starts. On the usual route I like to motor to 5 mph, and then pedal , so I can just stay in high gear and ride like it's a single speed. The usual route only has a stop every 2 miles, so on that route I let the motor work to get going.
All of it really improved my health. I used to get a lot of sinus infections, but now I spit out all the dust from work by the time I get home and don't get the infections. No dust, no infection.