Meh, that premise is bunk when it comes to podiums and wins. It only applies to championships. I would actually argue that almost all of their recent drivers have come up to speed quite quickly.
Massa, Kimi, Fernando, Seb, Leclerc, Sainz. All of these guys were scoring wins and/or podiums immediately. Massa won twice in 06, Kimi won his first race and became WDC in 07, Fernando won his first race, Seb won his second race, Charles would’ve won his second race in Bahrain (still won in Spa and Monza and beat Seb), Sainz scored 4 podiums and beat Charles in 21. Hardly gives the impression that it’s hard to get up to speed at Ferrari. Quite the opposite actually, there’s almost a rookie’s boost.
Hamilton is an outlier here in that he hasn’t got one podium yet, and the car is clearly capable of that much judging by Charles having 6.