That panel was tested and listed as an 18 circuit panel. The fact that you can physically cram more stuff in there is irrelevant.
Rats. I think you nailed it.
This is the main panel (only panel) for my house. 60A main on it. Trips about once every couple years when running power tools (simultaneously with other normal household loads) so I know it is not completely out of function. But yes, 1400 SF house, plus garage, all fed from a 60A main - I think this is the excuse I need to upgrade it. (Remodeling kitchen, these breaker spaces were to be for the two small appliance circuits.)
I shouldn't say rats, I should be happy. It's hard convincing the wife that good money needs to spent on maintaining things that are functioning but old. That stuff is out of sight out of mind to her, whereas I'm waiting for the other shoe to drop. This is not a huge expense and is long overdue.
Now if anyone has a compelling reason I can give to replace my one-hundred-year-old sewer line all the way across our basement, under the front steps, under the front walk, under the citcy sidewalk, all the way out to the street, I'm all ears. Had a plumber look at that and estimate it as a $20K job, not sure if that price even includes the new stairs/walks and landscaping. Sigh. Probably should wait for something bad to happen to make that fix occur. [EDIT: probably should wait until I just happen to have $20K sitting around! Yeah right.]
That was off topic. New main panel. Got it. Thank you.