Raikkonen finished sixth fastest after driving the car on Wednesday. His race in Barcelona was the first time he didn't score points during the 2019 Formula 1 season.
However, the team lost a significant amount of time on Tuesday as Callum Ilott crashed heavily. The car picked up damage, enough to end their day.
But Raikkonen drove 110 laps the following day to provide the team with lots of data. In typical Iceman style, he summed the day up well.
"It was a pretty good day in the car. After yesterday's issues, we had to change our testing programme slightly, but we managed to go through all the different things we wanted to try," Raikkonen said in an interview on PlanetF1.
"We had the chance to work with different compounds, we worked on the set-up, and we put a few different parts on the car, so it was a busy day. I feel if we did the race weekend again, we'd be stronger than we were," Raikkonen said.