The longest one I cut was 10hrs for the detail pass, I am making 6 of the gun calendars I have two more to go the detail pass on those are 4hrs. I have changed my brushes 3 times in 17 months and I have made alot of signs and flags. I blow out my router once a month.Still going strong.
I don’t remember which video it is but Phil with Paw Paws Workshop discussed this. He keeps track of his run ours between brush changes.