How do wildlife rehabilitators know when they can release an animal to the wild?

I’m researching the tools wildlife rehabilitators use and would love insight from people working in the field!

I imagine that the process of determining whether an animal is ready to return to the wild varies by species. Do you track their physical and behavioral recovery? If so, do you use pen and paper or any digital tools? What are the pros and cons of your current method?

Thank you!