I read a book by someone who was in control of tank production in the US during WW2 (who I cannot remember the name of) It was titled "the business of tanks" ( or something like that) the main jist was that the production of volume at uniform quality during WW2 was more important to tank warfare for the allies than perfection. The British kept tinkering with design as they went constantly making improvements this slowed up production, The German's produced designs that were so sophisticated and required so much exotic alloys and complex machining, The Russians had the best design but poor quality control. That left the US with a tank which although not perfect was able to be produced in reliably in large quantities.
The very first welding plant I had, I bought from my brother in law, it was a petrol driven Lincoln of WW2 vintage, One of his men showed me how it worked, he had repaired the shot up tanks during the war. They were first given a quick hose out and then a plate was clamped on the inside of the hole and they would fill in the hole with weld using one of these Lincoln welders, apparently the smell of roasting pork was overpowering during this process.