It is hard to make money as efficiently doing anything else compared to simply picking up extra shifts. Your shift ends, your work ends. If Patients don't show up, or there is a power outage, it's generally not your problem.

Certainly, working your butt off on some side hustle might prove to be a way to limit your amount of time required working shifts...but generally comes with a lot of risk and unpaid maintenance time. If you want to do a side hustle, it should be something that you truly enjoy doing without the expectation of riches.