My winder has a laser light to shut off, and if the sunlight it bright coming in the window it will override the laser. So now if it's in the sunlight, I put my hand in the way so it will shut off. Mine is adjustable, I can move the laser in or out to control how full the bobbin gets, or adjust it for bigger or smaller bobbins.
I routinely wind the unused thread onto bobbins for my regular machine and use them in piecing where it does not matter. Sometime I'll use the M bobbin as the top thread on the machine too.
I wind my not squishy, but I'm careful that it's not actually light. I got them too tight when I started and that gave me problems. My machine will also sound a bit rattly as I'm getting close to the end of the thread. I don't worry about it, and some times it's still 1/4 full so that is quite a bit of thread. I oil my bobbin race between each bobbin and sometimes I think it's also making noise because it's ready for more oil.