It depends on the amount and quality of the resins, pigments, and additives inside the can.
For one, check the paint company's material safety data sheets online to see how much titanium dioxide it adds to each can. The higher the percentage of this pigment, the better the coverage with fewer coats. Cheaper pigments, such as calcium carbonate, are less effective.
Here's how three grades of semigloss paint from one maker stack up.