Why are people trying to make predictions, there are none to be made, there will be a crapload of changes on every car before the first race. Everyone has specific parts to test the most here, some will have parts they worry about reliability under a full weight car with full fuel, others are testing a low downforce wing so going for pure speed.
There is exactly no knowledge of how much fuel is in any car, there is exactly no knowledge what type of run they are simulating, there is exactly no idea what the "best" time a car is capable of at this track.
The fastest car doing a dry run might do a 1:15, Rossberg might be doing 1;22's because they want to compare a run with the same fuel to see the difference on tyre wear between 15 laps at full pace and 15 laps taking it easy, and to compare fuel consumption at different engine levels, no one has a clue about a single reason anyone is doing the times they are doing...
With early testing the only reasonable assumption is, the more laps they get done, the more varying situations they can test the car under, and the more data they will have, for finding which parts are working and not, for reliability testing, for comparing efficiency, tyre wear and information for predicting strategys, outside of laps done and some pictures of car parts.... very little(if any) of the rest of the information is translateable to anyone outside of the team.