The thing with Unique that has kept it as a top choice for almost ten decades is that it simply isn't fussy.
It meters "indifferently," but the loads are still astoundingly accurate.
It has only really been in the past 10-20 years that people have "worried" about how Unique meters. Before that, they simply accepted a ±0.2gn variation and let the target do the talking.
Now, the shooters are so OCD about consistency that they reject many things without trying them. One of the main reasons to reload is to find what works for you and your gun(s) and not to simply make assumption.
You will find the 5.0gn and 6.0gn or Unique in many cartridges are very accurate loads.
However, my guns seem to prefer AA2 for light target loads and Silhouette for full power loads. Of course, the only thing I care about is accuracy and not some random power factor or recoil impulse.