If the system can freewheel, entirely possible to pedal 100% more, 400% more, 1000% more, whatever.
But I've found you don't have to carry a whole lot more battery to run just enough power to eliminate cogging for most dd hubmotors. 50w will do er, so lets say you ride 10mph without the motor helping much.
At 10 mph, 50wh to go ten miles using the motor only enough to eliminate cogging. For many, pedaling without assistance 10 miles is about the limit, excluding fit athletes. So all you really need if your system doesn't freewheel is a battery 50wh bigger. In theory.
But so tempting to make it a little easier, so 100wh more realistic for 10 miles. That can be 25% of a smaller battery, that has 400wh of real world capacity.
My approach remains,,, screw it and carry a big battery. I like to ride using 200w average a lot, but 50-100w is too weak for my taste. Once you are carrying 1000wh, 10 miles at 100w is only 10% of your capacity.
In any case, for me the most I'd improve my range would be 10-25%, not 400%. Likely only 10%, because I'm still just sick enough to be physically limited to that.
But you can choose to pedal all you want, especially if a bike coasts well. I do prefer a freewheeling hub motor, it definitely does better on the down hills, coasting much farther without pedal effort. I have done tests that proved that a freewheeling motor ridden on rolling hills gets efficiency very close to the same as riding on dead flat roads.
I just wish you could get gigantic 3000w geared hub motors.