Last weekend Leclerc took pole for Austin's United States Grand Prix, but was unable to convert that into a podium after losing the lead at the start and going the wrong way on strategy.
He ended up dropping back to sixth at the finish, but was later disqualified for excessive wear on his floor plank.
The end result masked what has been a stronger spell for Leclerc as both he and team-mate Carlos Sainz have gone through ebbs and flows with how much confidence their 2023 car gives them.
Ferrari's season has been plagued by inconsistent car behaviour over race stints, which it has gone to great lengths to address.
While Ferrari admitted it would need to wait for its 2024 car to find a permanent solution, Leclerc feels the floor tweaks the Maranello squad introduced in Japan have made a significant difference.
Leclerc is no fan of understeery set-ups, but that was what was needed to mitigate the 2023 car's worst behaviour and yield the best lap times. The Suzuka updates, however, have now allowed him to make fewer compromises on how he has to balance the SF23.
"All in all, it's exactly what I've been complaining about since the beginning of the season, where we have a car that is very inconsistent," Leclerc said.
"Once we get oversteer, we lose a lot of overall grip and this upgrade was exactly for that.
"That helped me gain a bit more confidence and to set up the car in a way that I prefer, and to have a bit of a stronger front, which normally is something that I enjoy.
"I just feel more at ease with the car since then. But there's still quite a few races left and there's still quite a lot of work to do. We need to keep pushing, but we did some steps forward, for sure."
The updates have helped Leclerc get on par and perhaps even gain the upper hand on Sainz, who had been Ferrari's best performer in the three races following the summer break, before the Japan floor arrived.
But team boss Fred Vasseur thinks Ferrari's car changes will help both drivers achieve the balance they prefer rather than favouring one driver over the other as an unintended side-effect.
"We can fine-tune, and we can find a compromise and a good solution, and a good balance for both sides of the garage," Vasseur said.
"We are speaking about hundredths of seconds. Charles was on pole in Spa in front of Carlos with the old package and each weekend from Spa we are speaking about hundredths of seconds.
"It's not that we are changing completely the approach, sometimes it's a driver mistake, sometimes it's set-up mistakes, but we are into the fight for one tenth, at least in qualifying."
Additional reporting by Adam Cooper
