Again, it's not a place to skimp. What does RPM have to do with it? You can have frequency issues at any RPM. Not just high RPM. Don't step over a donut to pick up a dog turd. You see what happens to rubber over years. Now, change the bob weight, change the RPM, change the load. All those change the frequency where issues can occur. The harder you work the rubber, the quicker it becomes hard and fails.