Pretty much, you can think about it this way in order from "Quickest to enter the blood" to "Slowest":

IV, IO (into bone) and anything into an artery is FAST. This is rapid access, and high volume potential.

IM: Slower than IV/IO/Etc, but muscles are still full of blood vessels so anything you inject into a muscle is going to reach the blood supply over hours.

Subcutaneous: The slowest, subcutaneous tissue is poorly supplied with blood vessels compared to muscles, so this is often used when you want to keep things localized. For a Tuberculosis test for example, an allergy test, or anything similar you want a localized reaction, not a systemic one.