Sustained creativity is an interesting concept that I recently discovered.
I was watching the Talking Heads concert movie, Stop Making Sense (directed by Jonathan Demme, 1984), when it struck me how brilliant the band, led by David Byrne, was for a few brief moments in time when they recorded the movie--actually it was probably a few years that the band was at the top of its game. But in a few years, the band's burst of creativity had ended. Though they are all still around in different groups, no one is making music as great as what they produced for Stop Making Sense.
Now in another context, I recall writing to Maya Angelou and commenting on how it is often the case that one's artistic focus could shift from poetry to prose over the course of a long lifetime, a shift in unsustained creativity. The bursts of creativity could dissipate, disappear, continue or alter.
In any case, one may wonder how difficult is it to sustain a high level of creativity over a span of years or decades. The Beatles did it for what, maybe give or take ten years (probably closer to 8). Emile Zola did it for forty. Monet and Picasso produced art work over spans of decades, but how much of it was any good? Ten years for Led Zeppelin. Four years for Boston. Maybe twenty years for Pushkin. Eight years for Joe Montana. Most artists do not continue for long.
While some may argue differently, I think that it is pretty clear that over the course of his long life, Lev Tolstoi never really equaled what he did with War and Peace (1869) and then in Anna Karenina (1873-1877) in that brief, hectic span of ten years even though he remained a giant of Russian literature until his death in 1912. His later works included the Kreutzer Sonata, Resurrection, The Death of Ivan Il'ich, etc. These are certainly great works in their own right, but not great works on the level of W&P and AK.
So again, it struck me how difficult it is/was to sustain a high level of creativity over an extended period of time. (Rock music is filled with stories of one hit wonders, including The Wonders aka The Oneders.)
So I came up with the idea of "sustained creativity" to apply to the cases of artists, bands, poets, philosophers, writers, creators who have been able (or not able) to operate at a superior creative level for long periods of time.