As i remember they were surprised in '18 by their lack of performance on softer tyre circuits and assigned some of that surprise to a lack of pre-season testing on the softer tyres. I imagine they decided a year ago to make sure they did some running on all compounds in future.Mandrake wrote: ↑21 Feb 2019, 13:36Mercedes doing a deviation from their routine of previous years by using all rubber compounds and chasing faster lap times. They were very happy with just running the mediums the last 2-3 seasons in pretesting.
Whatever triggered this change of program.....it is certainly a different approach. This might indicate more than any laptime that they are less sure about where they stand.
Related to above, do teams have to "pre-order" the tyres in advance for these tests as they do for races? (albeit with a much shorter lead time than the race tyres).