How long does it take to become an Old Master?  Longer than
one might think:

Louise Bourgeois, a great experimental sculptor, once declared
‘I am a long-distance runner. It takes me years and years and years
to produce what I do.” Bourgeois made her greatest work after the
age of 80. When she was 84, and an interviewer asked whether she
could have made one of her recent works earlier in her career,
she replied, ‘Absolutely not.’ When he asked why, she explained,
‘I was not sophisticated enough.’


Old age and experience may be lethal for the creativity of
conceptual young geniuses, but they are the lifeblood of the
innovations of experimental old masters.”