Calibrated a Befaco Pony oscillator with a cheap multimeter with a one-and-maybe-a-bit decimal place voltage accuracy earlier in the day, with reference 2.5V base going from 60c drift across 3 octaves to about 23c.

Got a nice modern multimeter for 20 quid, and going to 2.500V exactly has got that drift down to under 5c. I'm really happy with that, even though it's way too much multimeter for me...