The American useage is 'Ring and Cylinder', and the English useage is 'Platen and Anvil'.  Your theory is lovely, but there is no laziness.  This adjustment would have been set at the factory, and there would normally be no need to disturb it.  In theory, it may have to be adjusted when a replacement platen is fitted, but in practice, the platen supplier would know the exact diameter that the platen should be (as well as the correct rubber grade) and would grind it to the correct specification.  Some machines did not even have a ring and cylinder/platen and anvil adjustment.  A good example of this is the Corona and Smith-Corona portables.  Others had the adjustment sealed at the factory in such a way that it was impossible to change it (Imperial standards).  The reason that hole-punching is seen so often is purely the age-hardening of the rubber.  You never see this on a typewriter fitted with a cork platen because cork does not age in the same way.

thetypewriterman wrote:

The American useage is 'Ring and Cylinder', and the English useage is 'Platen and Anvil'.  Your theory is lovely, but there is no laziness.  This adjustment would have been set at the factory, and there would normally be no need to disturb it.  In theory, it may have to be adjusted when a replacement platen is fitted, but in practice, the platen supplier would know the exact diameter that the platen should be (as well as the correct rubber grade) and would grind it to the correct specification.  Some machines did not even have a ring and cylinder/platen and anvil adjustment.  A good example of this is the Corona and Smith-Corona portables.  Others had the adjustment sealed at the factory in such a way that it was impossible to change it (Imperial standards).  The reason that hole-punching is seen so often is purely the age-hardening of the rubber.  You never see this on a typewriter fitted with a cork platen because cork does not age in the same way.

Sir - thank you for your patient correction and instruction.

It is worth it to be proved an over-confident tyro yet again, to learn something! 

Another thing I found, in a 1940's repair manual, was the recommendation that if a platen were ground down more than 0.01" from its original diameter it should be discarded. Easier to come by a new platen then, for sure. But makes me wonder about the recommendations to condition platens with mild abrasives. Maybe it's more difficult to remove one hundredth of an inch of rubber than I think?
 

Re: Cork Platens.  This was traditionally offered as an alternative to rubber.  It does not deteriorate in the same way and can still be fine after 70 years.  The down side is that the grip on the paper is never as good as rubber.  Maybe 5% of typewriters had cork platens and feedrolls, but during world war two the percentage increased dramatically due to the shortage of rubber.  The Imperial Typewriter Co. were allowed to continue manufacture throughout the war and towards the end, they had to get very creative with cork.  I have seen a couple of 'War Finish' standards with special cork feet, and recently a wartime Good Companion with cork foot grommets.  The carry case did have (perished) rubber feet, presumably because the factory still had some left !