I have started a program where I accompany the maintenance people on their grease PM's for a handful of critical 24/7 equipment. I go down the machine and record "as found" ultrasonic readings and determine which bearings need grease. I listen while the grease is applied and stop the addition when a step change is heard. After lubricating all the bearings on the machine I go back and take additional readings and add more grease if I feel it is warrented. I recently bought a $2.50 headphone splitter so the mecahnics can also hear whats going on in the bearings when they apply grease. Works great and has eliminated grease related failures for 2+ years.