Instead, teams need a structured programme, so each new item or change has a run to compare against. That way, teams can see if the comparison is good, bad or indifferent, and can then progress forward with whether to go down that route or not.
Testing is an opportunity to focus on broader, bigger picture changes to the car. There's so little time on a race weekend, practice is mainly focused on the details - qualifying balance, energy deployments, single lap pace, race set-up, engine cooling, tyre windows. Those are just a few examples...
There isn't much opportunity to conduct deeper investigations over a race weekend and that's where testing becomes vital. It's also a chance to re-correlate simulations to the data and information you collect over the test. Windows to do that don't come around very often during a season.
The Circuit de Barcelona-Catalunya is just the kind of track you want to test on, and that's why it's the winter testing venue year after year. It contains every kind of corner you could want, from high speed sections to low-speed hairpins. This makes it a challenging and demanding track for a Formula One car, putting it through its paces.