On my rural department:
There is a huge push to get us going. It's an average of 42 minutes to the hospital (less if people want to go to the county hospital, but they have trouble handling anything more than a minor illness/injury--their handling of cardiac arrests has caused our chief and medical director to question whether they are an "appropriate" facility when we're to go to closest/most appropriate). Most runs are under 20 minutes unless we are doing a refusal b/c we have to collect all the info before leaving. I know this due to us getting a checkup at the 20 minute mark. The only exception are those large patients, patients who are on a trail that is hard to access, extrications, and cardiac arrests (where a scene time of at least 20 minutes is mandated by what we need to do from the protocol).
On our primary truck, it goes something like this for someone who knows they want to go (times rounded up to the nearest :30 based on 2 calls I kept track of time for):
0:00 Arrive on scene
1:00 Pt contact made
2:00 CC determined, vitals started by second man while first is getting hx. Third man assists as necessary
4:00 hx, vitals finished. Determination to go to hospital made. Discussion of where to go done.
5:00 Third man get's gurney, second man helps collect pt meds, patient info or belongings. The meds and any pt info will be read at a later time in the truck. If this is not needed, he goes to spike a bag in the truck if one is not already spiked. In-Charge hooks up a 12-lead patches/wires (but not attached to monitor)
6:30 Gurney is back, everyone helps load patient onto gurney.
8:00 patient is loaded onto truck.
8:00-10:00: any interventions that need to be done before movement are done sitting in the truck (like EKG, some medic prefer one attempt on an IV before moving). Then we get underway. We often keep the driver in the back until we are ready to go to help with things.
Obviously any interventions that we do on scene will prolong this, but we usually keep it under 15 minutes for a medical call.
When I run as in-charge of the squad, the only changes I make are that I obviously don't have as much equipment to take with me. And other than vitals, i rarely do anything on scene for a medical call. Since I need medcon for a 12-lead anyways, we can pull over and do that enroute. My scene times are averaging at just under 10 minutes right now even though my truck is always only a 2-man truck. I also take the cot in initially on patients that I know are frequent fliers (since our response time can be up to 40 minutes to some parts of our district, I have a lot of time to look these things up on the computer on our way there).
At my city department, things are much slower:
The crew I usually works with likes to sit outside someone's house for 20 minutes at a time doing interventions, starting the IV, etc. This is because our MD is a lot more strict with the protocol, and if you get to starting an IV, you better have everything above that line on the protocol done. It seems kind of ridiculous to me since we can be at the hospital in about 5 minutes, 8-10 minutes in traffic, but they like starting their IVs and playing with their monitor so they sit there and do everything on scene. Another crew I often work with does the opposite. The minimize on scene time, but then we sit in the hospital parking lot for ages waiting for them to finish the CYA stuff.
Often, on BLS runs, the medic will put me in charge (especially if it's close to dinner time) as this means less CYA stuff to be done. On a recent patient, we couldn't have been more than about 5 blocks away from the hospital so all I got done were vitals enroute. He was very stable and was asked to call 911 after having dialysis that day for having a low platelet count. I might get dinged for not checking his BGL, but on second thought, I might not because I did nothing in the protocol below that line so it simply could have been I didn't have enough time to check it before arrival.