Time to remind you what a bargain an anode is. It’s $40-50 vs $1600 or more for a new water heater. You should at least check and maybe change the anode right when the heater goes out of warranty. Do that and it will never rust out.
If you’re using a softener, though, you ought to check every couple of years. It’s not always true, but it’s common or softeners to speed up anode consumption, sometimes drastically.
My own was 42 years old when I moved out of my house in California because we had serviced it as we recommend on this site.