Given that he only drove in the afternoon, we'll label Valtteri Bottas as Tuesday's marathon man, with the Finn covering 102 laps around the Circuit de Catalunya.
While Lewis Hamilton's morning work with Mercedes focused on aero data collection, soft tyre compound analysis and general setup work, the Finn completed a race simulation before rounding off the day with further aero tests.
"I think it was another good test day for the team," said Bottas.
"We did so many laps again and completed all the runs that we had planned to do. I worked on race simulations this afternoon. It was quite tricky with the windy conditions but I'm sure that we can learn a lot from the data."
Mercedes new recruit had a big moment at Turn Nine but fortunately remained clear of the barriers!
"I had a small off but it wasn't anything serious. I lost the rear end with a gust of tail wind that was quite sudden. This is testing - you need to find the limits."
Half-way through the first week's programme, there hasn't been a worry insight for the Silver Arrows squad which continues to dial in its potential.
"It's interesting to learn more about the new car - not just for me personally, but for us as a team. All the set-up work we've done has been very valuable. Two more days to go - I'm looking forward to it."
GALLERY: F1 drivers' wives and girlfriends
Keep up to date with all the F1 news via Facebook and Twitter
Charles Leclerc believes Formula 1's new-era machinery has forced him to rethink one of the…
Formula 1's teams and drivers regroup this weekend surrounded by the majesty of the Ardennes…
Max Verstappen has once again refused to reveal his hand on his Formula 1 future,…
Aston Martin is facing a race against time at Spa-Francorchamps, with the team's ambitious push…
Red Bull has opted for caution over innovation ahead of this weekend’s Belgian Grand Prix…
Max Verstappen has made a significant move away from the Formula 1 cockpit by welcoming…