welcome to the forum. On my 2013 Road Glide I changed my front pads at 60,000 and they still had a little life left in them. The rear were original when I sold at 68,000.
On my 09 ultra I still have the original pads all around with 34K on the clock. I could probably get another 6-8K out of them but may change them this winter. I don't use the engine for braking unless I'm riding in the mountains. Figure I can change the brake pads but would not have the ability to change a clutch, so I use the brakes more than most people would. Been researching EBC semi-sintered pads for replacements.
On my '98 Road King, I did not change the front pads until 95,000 miles. I was shocked. Tons of highways miles though and mostly one up. Changed the rears at every other oil change.