Ever thought about what you would do if you are shot? Stabbed? Ever considered what you would do if help was a long way off?
If you work in a rural area, you may have considered that EMS may take 15 minutes, 30 minutes, or even longer to get to you. If you work in an urban area, those time delays may not seem possible, but they are. Consider the officers shot in the infamous Bank of America robbery in Hollywood, CA. Wounded officers were pinned down, and help could not evac them for a very long time.
You have to be able to provide for your own medical care if you are wounded. Circumstances or location may prevent a speedy EMS response, and until they arrive, you have to stop the bleeding, close the sucking chest wound, or otherwise stabilize yourself.
Most academies are teaching some form of First Responder program to new officers. But, when is the last time you had any refresher training? First aid skills are like any other: if you are not using them, you will lose them.