im measure Freq quite rare
and very dissatisfied with all internal oscillators. as it need many hours to stabilize when turn ON, and even 8D direct counter most likely 2 last digits will be incorrect.
cheap OCXO well insulated with Vref like LT1021-5 , after a reasonable time to age , gives -10 per year stability and no jitter.
high stability OCXO inside an equipment, required constant ON condition, so like meter off but not a reference. in my case usage are few times per year , and it doesn't make sense to keep it running. so i decided to build external 10M ref that constantly on, well Insulated OCXO consume around 20ma on 12V vs 120mA open space, and significantly lower jitter, as a thermal loop control do it much more precise, due to less heating loss.
as well as I noticed for quartz oscillators need approximately a week to get stabilized (stop drifting) after extended offline period. so adjustment better do after long period of ON or STANDBY .