Early lithgows stocked in walnut and Queensland maple never had the plates installed but I suspect crushing of the draws where the plates would be installed would have been an ongoing problem. The wood compressing from recoil develops into a loose action to forend fit and the problem escalates in to far more serious problems. In the late 20's lithgow started fitting walnut inserts as pictured but this process only continued for a few years between 1926 and 1929. After the lull in production between 1930 and 1934, they introduced the steel pin method also pictured but this method was also short lived and presumed to have only been fit to rifles assembled in 1935/36, probably only a few thousand rifles maybe less. The copper plates were introduced some time after this but its not clear to me when exactly. Certainly by the time coachwood replaced maple in 1940, the plates were in full production, but the time lines of its introduction are often blurred because many much earlier dated rifles then had them installed later, including those stocked in walnut. About mid 1943 they were omitted from assembly to speed up production but were reintroduced once again 6 months or more later when it was realized they were an essential component for the rifles longevity and effective operation in the field. This little period of time equates to tens of thousands of rifles assembled without the plates and many of these are in circulation today.
I'm sure the time lines of all this would be evident in the LOC.
I think the plates were a good fix for an ongoing problem and obviously they thought they would be an improvement to walnut stocks also, which I tend to agree.
Damage to the draws can often be identified with an external examination of a rifle, by a crack along the underside of the forend, starting from the large trigger guard screw, but not always. If you see this crack, its almost certainly beyond traditional repair by a Commonwealth armorer.
Sorry I was unable to post images.