Magnussen finished in P7 in Barcelona at the weekend, where it mattered, and helped "gather a lot of data" for Haas in the in-season testing at the Circuit de Catalunya.
The Dane recorded a quickest lap-time of 1:18.101 and that was 2.3 seconds slower than the fastest of the day, but the Haas driver confirmed they were not taking part to set a best lap-time.
"I was happy to get a lot of laps on a test like this straight after a race weekend," Magnussen explained. "It's really useful to be able to evaluate everything back-to-back.
"We've tried some interesting stuff and gathered a lot of data to go through. We're not chasing a lap-time; we're giving specific feedback and gathering data."
Magnussen went onto say how useful the two-day test was for the team, who secured a double-points finish at the weekend.
"Some things were good, some not so, but it's testing, so we're trying stuff that's not necessarily going to make you faster - you're just getting information to help you make progress," Magnussen concluded.