Medical workers are expected to attend assigned clinics. While in clinic, we expect practitioners to help triage patients, set up clinic and see patients using the provided means of documentation. 
Non-medical workers in the field are asked to help in a variety of ways - from running errands to pharmacies to assisting practitioners. 
While we do our best to give everyone a free afternoon, this is not guaranteed. 
Prior to our trips we do ask our practitioners to help fundraise for money and supplies as this is how we are able to provide for our patients.