[time-nuts] Allen deviation? Yes indeed that subject again

[paul swed]

I have been looking at the subject of Allen deviation and this has been
discussed numbers of time on Time-nuts.
But my question is this.

If an oscillator is stable in frequency but shifts phase 90 degrees and
then comes back in a short time. From my reading I don't think that will
show up in a typical Allen deviation plot that runs 1000s of readings at 1
second intervals. Typical HP5370 test setup. I think this capture approach
will miss the issue.

How often? Correct phase .5-3 hours, shift 5-10 minutes it seems random
actually and the duration varies.
Am I looking at this correctly?

Regards
Paul
WB8TSL