STL FSDO is one of "those" FSDOs that takes their own view on the regs. There are plenty of horror stories from some local flight schools and 135 operators as well.

Ok, after some additional research, I may be wrong. I thought we had discussed this before, but the articles I found suggest otherwise. They are old though (circa 1997) so I don't know it has been superseded. I doubt with today's schedules anyone would want to instruct for cash on their free time anyway.