Something else that I do is on my first spool-up of the day, I have my blades slightly loose (but still tight enough so that the shake test will move them) in the blade grips and run my head speed up in IU1 at zero pitch. I then hit throttle hold while maintaining zero pitch. I let the blades spin down and stop on their own and then I tighten the blade grip bolts tight. No more shakes for the rest of the day.