As a freelancer, I honestly prefer charging hourly / daily / weekly. The type of project I do tends to have an ever-expanding scope. Charging by project would

As a freelancer, I honestly prefer charging hourly / daily / weekly. The type of project I do tends to have an ever-expanding scope. Charging by project would put me in an adversarial position with my client; I'd be forced to always push back when the scope / situation changes. By contrast, charging by the hour lets me say yes much more often. Of course, if I were to do more "turn-key" projects, scope would be much more predictable so it'd probably make a lot more sense to charge per-project.