I finally had ours pumped a couple years ago, after procrastinating severely since we built the place - and I know better, since I also have to dabble with septic things now & again for work. I think it had been a year away from 20 years. And it was pretty full, the pumper earned his way that day. Field still doing OK, but suspect either we got lucky, or it is about ready to bung up.
The thing that really grabbed me was all the
baby wipes in the bottom. After raising 3 kids - that was a lot of wipes. Those things don't degrade at all, despite what the package might claim - they looked like the day they got flushed. Very ugly.