originally posted by JD-EE ...
You can, however, find nice stable resistors that hold 0.1% or less over temperature. You can also find nice "NPO" ceramic capacitors that hold within a few dozen ppm/degree C. That's where the temperature variation would come from. Manufacturing tolerances of the capacitors would have to be in the 2.5% range or else trimmed with a parallel resistor for the R in the RC that is calculated and soldered in during manufacture. For reasons of cheap getting it within 1kHz or about 2.5% is "good enough."
So long since I messed with oscillators, that the KISS principle deserted me! A fundamental frequency oscillator combined with a simple divider chain for other timings, and all well within specs, is as you say "good enough".
mm43