Every field of study requires time.
Professional violinists and piano players practice 16 hours a day.
Alekhine we know was always with a portable chess set practicing.
When it comes to time, it is not time studying but rather quality time studying quality subjects or in our case chess subjects.
Fischer indicated he was not a great player. Just happened one day he became a great player. Probably from quality study of "64", "Chess in the CCCP" and other publications. Going over each game.
When it comes to time, there must be quality study.
Whether the subject is music, medicine, law, or chess.