A test suite would be designed to call every routine in a project a limited number of times. This means the JIT compiler will be compiling each routine, for it

A test suite would be designed to call every routine in a project a limited number of times. This means the JIT compiler will be compiling each routine, for it to be run a few times then thrown away. Realistic loads might have the same routines run more intensely and might see more benefit from the JIT compiler.