Thanks for the feedback and great question here.

PRs are still attached to an hourly or flat rate that you and the client have agreed upon. This means you will not make more money for submitting more PRs. You just receive your payments sooner.

The client also approves your pull request to trigger the payout. The minute your code is accepted into their codebase you receive payment.

I'd love to hear more thoughts on your concern here and if this solves it, really great insight.