I'm currently in FD (Lifeguard), and I think the only thing I have to say that sucks is when we go on scene, spend a while roleplaying etc with the patient, take them to hospital and then not even an hour later we see them running around, jumping, doing everything like the past incident never happened.
Now I get it, roleplaying injuries can be boring if there's no one to RP with in the hospital, but if there ARE people on duty please roleplay with them, give them RP. If there is no one on duty at the Hospital then at least roleplay for the rest of the day (And potentially couple more depending on injuries), the aftermath of said incident. If you've been shot? Don't go back shooting the same day and acting like it never happened. Jumped off a building? Don't then go running an hour later.
On scene however, I love reading the scene and trying to make things a bit more light hearted IC, especially when people roleplay being scared etc. My character doesn't want to just bag someone up and leave, I prefer providing roleplay and ensuring those who are on scene understand whats going on. So if you don't know vitals or what injuries to do, or how to RP I often pm the person with advice as well as explain what I'm doing and what could happen. For those who have never been in a medical faction and have no experience with medical incidents IRL it can be overwhelming with 5 people asking you different things. The only time I'll try and hurry things up slightly is if someone is clearly not enjoying what's going on and aren't happy to roleplay, since it makes no sense to spend extra time on a situation people aren't enjoying.