And 10-15 years, at a time when most were lucky to make their mid forties, is roughly 25-35 years for us today. Building a stone castle was always a generational endeavour.
This is a common misconception. Life expectancy at birth being low reflects high mortality for infants and children. If you can make it into adulthood, most people lived for a relatively long time.
https://sc.edu/uofsc/posts/2022/08/conversation-old-age-is-n....
OK... 25+25 = 50 rather than 40. But that is for the wealthy, the top percentage who owned land. Everyone else would have been less. That is still about half of what we can expect today.
The average adult lived to what we’d still consider old age - the average life expectancy of all humans was ‘just’ low because child mortality was high, and even most child deaths occurred at very early ages.