[pbronez]

It’s tricky because there are subtle psychological effects when marginal use directly incurs marginal cost. It makes each use a decision.

When you assemble tools for cognitive work, it’s important that they have low overhead. Thinking about the financial cost of using a tool is a small context switch that slows you down. Thus a bundle of prepaid stuff increases the utility of the service beyond what you’d get with pure pay per use, even though the latter is more economically efficient.