An apposite quotation from J E Littlewood’s “Mathematician’s Miscellany”—not talking about the exact same thing as here, but related:
Speed in creative mathematics. I say there is a speed over 10-20 seconds, 10-20 minutes, 1-2 hours, 1-2 days, weeks, months, years, decades. And people can be in and out in different classes. With a collection of really difficult problems, nothing happens in a year; much happens in 10 years. (This leaves the beginner cold.) [...] At a guess I should say I was (1960) quick over 20 minutes, 6 weeks, 1 year.
(My memory of this is that he originally wrote “the same man”, not “people”; either my memory is wrong or the edition I have now, more recent than the one I read first, has been updated in line with modern sensibilities. “The same person” seems like it’s actually the right phrase.)
An apposite quotation from J E Littlewood’s “Mathematician’s Miscellany”—not talking about the exact same thing as here, but related:
(My memory of this is that he originally wrote “the same man”, not “people”; either my memory is wrong or the edition I have now, more recent than the one I read first, has been updated in line with modern sensibilities. “The same person” seems like it’s actually the right phrase.)
[EDITED to fix a typo.]