Here’s a tip I’ve learned from many years of routing: when you prepare to make a cut, always cut a test piece first, and measure the result to evaluate your bit setting. There are all sorts of variables that can impact why the bit setting you’ve painstakingly dialed in may not produce the actual cut you want (insert plate isn’t flat with tabletop; bit slips in the router; workpiece is slightly out of flat; feed pressure is uneven, etc.). So, set the bit height to approximately where you want it, cut, measure the cut, adjust the bit, and cut again to fine-tune your bit setting. After all, what ends up in the workpiece is all that really matters.
– Bill Wells