The video in the interesting question How did the GoFast 2014 Rocket de-spin? shows a de-spin that went well. An initial very fast spin (for stabilization during propulsion) is almost perfectly de-spun during a maneuver that is so fast that it is hard to imagine it could be anything else but a Yo-Yo de-spin.
The mathematics behind this is summarized in this answer along with links to several original sources. Briefly, $r$ is the ratio of final to initial angular velocity, and will be zero at perfect de-spin but can still be positive or negative for undershoot or overshoot conditions. The remaining terms are described in detail in the link.
It's a balance. So if the final angular speed is much much lower than the initial (near perfect cancellation), it suggests that both the initial spin rate and the de-spin were well controlled.
But what if the initial spin had some uncertainty that could not be controlled?
Question: Has adjustable Yo-Yo de-spin been tested or demonstrated? Reading about a serious but untested proposal would also be interesting.
I can think of all kinds of possible ways to do this, last-second laser trimming of the wires, or just a clever break-away release, vernier yo-yos (say 10kg plus 160g, 80g, 40g, 20g, 10g independently addressable "fine yo-yos") but this kind of complexity really defeats the elegance and reliability of the Yo-Yo technique with fixed mass weights and premeasured wires, so maybe backup thrusters to re-adjust the spin before Yo-Yo would be a better way to stay with known technologies.
Still, have variable Yo-Yo's been tested or demonstrated?