In the last year of regulations gaining 0.4 seconds is solid I would say. Remember how hard it was e.g. for Red Bull to find any gains last season. Besides the McLaren Miami update I can't remember any update that moved a team significantly forwards from one race to the other. It's all a process over weeks and months.
I also think keeping the good characteristics in the car is equally valuable than just net time gain in the simulator. Having a big setup operating window, taking curbs as smooth as possible or good tire saving behavior can also win the championship this year.
I really hope FER can retain all these strengths and maybe make the tire warm-up at colder tracks a little better. Than this car can be a championship challenger.