I've yet to reach the end of an Eagle XX1.
With the first generation non Eagle XX1, I used to replace the whole transmission every 9 months.
Although I had to change the cheap Aliexpress ring on my FM936 recently, but the chains and cassette are still fine.
Two things have changed since I'm using Eagle chains on my gravel and MTBs.
I rotate 3 chains on each randomly. And hot wax them all together.
It takes about 2h of distant attention(swapping chains every 10' or so) to make 9 to 12 chains.
I started waxing when Marcin from AbsoluteBlack advised me to use squirt in an email.
And then saw the Australian youtuber hot waxing chains.
I always travel with 3 freshly waxed chains, and a small bottle of UFO drip in case of wet rides.