Eyebrows were raised when the Citizens paid just shy of £50m to sign Stones from Everton in the summer of 2016, and the centre-back struggled for consistency during the 2016-17 season.
The 23-year-old has been in impressive form for Pep Guardiola's side this term, however, and has also contributed three goals in four Champions League appearances.
"I don't think there's ever been a point where I haven't been developing and learning. That doesn't mean it's always been good. I have had to take dips and take a good look at myself," Stones told reporters.
"I feel every day I go out on the training pitch there's something to get out of it. Not just me, all the boys all have that same mentality so that is why everyone is performing for their club. I have been on a good run personally and I want to keep that going."
Stones is currently with the England squad ahead of their upcoming friendlies with Germany and Brazil.