Technology leadership before mass production

Why did Britain and the United States often prioritize technology leadership before quantity?

They sought to enter mass production from a more mature technical base, accepting initial numerical limits in return for a later reliability and capability advantage.

The calculated sequence was to continue developing technology, then commit to mass production at the latest workable point. Britain entered mass production from a somewhat more mature technical base, and the United States later used a similar logic on a larger scale. German and Italian designs entered production earlier or emphasized impressive performance before reliability and manufacturability were resolved. The gamble accepted an initial shortage of numbers in exchange for equipment that could be improved, standardized, and produced effectively through a long war.