My point about cut in speed is relevant because its part of a spectrum. The tangential speeds between small and large have similar speeds in the spectrum BUT the target voltage, whether you are single phase or multiphase, your wiring method being either serial or parrallel, etc. all impact your voltage. So you figure out your battery limitation, then figure out a single coil performance, then configure from there with your design. Whether your coil makes 1v, 3v, or 13v is only relevant once you have an application such as a battery to design around. The advice you are getting is akin to master mechanic advice. You either accept their experience or stumble through the exercise. There really is no shortcut. Believe me, its a fun process to tinker. Once you build something and it works, you stop tinkering.