So, here’s the math for expected value, that is, the average number of ticks you’d get rolling the listed dice:

4 rolls:

-2 dice: 8.5

-3 dice: 9.8

-4 dice: 10.9

-5 dice: 11.9

5 rolls:

-2 dice: 10.6

-3 dice: 12.5

-4 dice: 13.6

-5 dice: 14.9

Looking at that, I think 4 rolls is more appropriate. At 5 rolls, it takes bad luck to fail even if you have few resources devoted to building, and it’s basically a sure thing if you do have those resources. At 4, folks without rig and laborers have an uphill climb, and folks that do have rig and laborers can still fail if the dice go particularly wrong.