Ran across this suggestion in Audio Amateur magazine, late 1970's. "Helper" caps were intended to make up for the - then - deficiencies in large filter caps to decouple hi frequency signals in hi fi amps. And the ratio was generally 100:1.
I've tried it in a couple instances in guitar amps when I thought the regular filter caps might not be enough. Didn't help much. Some boo-teek amps might have these. If it was such a revolutionary improvement, everybody would be doing it now.
Digital circuitry otoh often does include local bypass caps besides main filter caps. You'll see 0.1 or 0.01 uF caps tacked here & there on some digital circuit boards power supply rails, a cheap way to keep the power supply voltage clean well into the GHz range.