Premier League champions City began the campaign with a 3-2 win over Southampton at the Etihad Stadium on Sunday afternoon.
However, England defender Lescott has insisted that all the sessions are necessary if they are to retain the title this time around.
"Long day's training today, not many teams doing double sessions still," Lescott wrote on Twitter. "It's a must if we aim to better last seasons achievements."
City's next match is a trip to Liverpool on Sunday.