When there are lots of driver changing seats you need 4-5 races compared to 20 years ago it was 1-2 races maximum.
The budget restriction on sims, wind tunnel, track time makes it impossible to get the driver, crew, and car on the same page.
They just can’t get enough hours to set up cars differently, so by default they have to make both cars match the primary driver in the beginning of the season. Especially if he’s a carryover. They need both cars data.
That hamstrings the second driver immensely with a new team.