The Mosquito was noted for it's smooth skin, while some all metal aircraft had good finishes, many others did not with dishing between ribs or stringers and such. Some wooden aircraft also had finish problems, especially as they aged.
It is a bit of a crap shoot. Spend tens of thousands of hours designing the structure for an all metal mosquito and the jigs and tooling, then train a work force to be more careful in assembly than on many contemporary British aircraft. To gain a how many percent increase performance? Single digits?