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I doubt even high end rigs try to be accurate without calibration, too much possible variance in the parts used.
Especially if they are switching between multiple crystal vendors.

Sounds like hfsigs might be pre-calibrating the new uBitx, if calibration is an issue for some.

With Allard's possible v2 firmware someday soon for the Bitx40, we will drive both the bfo and vfo
from the si5351, making it possible to have the calibration remain correct across large frequency ranges.
(Currently the VFO error is proportional to frequency, the bfo error is a fixed additive error in that 12mhz crystal oscillator).
The bfo can be placed into the center of the crystal filter passband during calibration, making zerobeat easy to hear even on weak signals.

So with v2 firmware, my preferred method for calibrating a Bitx40 would be to short across the 7mhz bandpass filter,
then calibrate for a zerobeat with WWV at 15mhz, watching the audio with a scope so I can see it down to very low frequencies.?
Could add a header pin at each end of the bandpass filter, so it's easy to add in the wire jumper.
If you don't want to add the wire, just calibrate to one of the 41m shortwave broadcasters.
Very easy to do, and can be very accurate.

The uBitx could be calibrated in a similar way, but since it covers all of HF there is no need for a wire.

I previously wrote: ?
? ? I'd guess two otherwise identical crystals with a different load?
? ? capacitance spec would be cut by the manufacturer for slightly
? ? different frequencies, that's all.
? ? An error in the load capacitance spec of the crystal stuffed into the Raduino shouldn't matter one whit
? ? if we can calibrate it out using a multiplicative correction factor, as Allard's recent firmware releases do.

There's quite a bit more going on here than that suggests.
For a given crystal, there is a range of load capacitance for which it will oscillate, beyond that it does not.
If curious, here's some resources for further reading:
? ??
? ??
? ? EMRFD

Jerry, KE7ER