It was somewhere outside Barstow when "Bob" wrote:

Isn't there a mark on your joiner that has settings on it for 10's 20's
etc.??

There's usually a rotating cam, but there's also a screw adjust in the
stop.

If you buy a cheap biscuiter then it's worth checking this, as they're
often inaccurate. I've recommended Screwfix's Ferm biscuiter to a few
people as a really cheap but usable machine, and then had them report
problems with it. Fixing this adjustment solved the problem.