I was just using my bench grinder today,it reminded me of something I learned years back.
I worked in an auto shop when I was younger. We had one of those wheel balancers that spins the tire and rim at a high speed,then tells you where to mount the wheel weights. We had a problem where we would burn out the motor on our balancer about every 6 months. One day the repair guy who came in told us to spin the wheel/tire by hand before we we hit the button to start it spinning. He said that motors draw their most current at O RPM,so if we gave it a little spin before we started the motor it would extend the life of our motor. Well,I worked at that shop another 3 years and no more burned out motors!
I've applied this theory to my bench grinder since I bought it new years ago. It's just a el cheapo grinder that I bought about 20 years ago,BUT I bought one with big heavy grinding wheels,and quite a big motor. I've been in the habit of giving this heavy wheel a spin before I turn it on,and it still runs great to this day. Would it still run if I didn't spin it before I hit the go button? Who knows,but it's lasted me quite a long time for a cheap grinder.