Typical summary log is:

Project Example build #1234: STILL UNSTABLE in 1 min 12 sec: http://example.com/job/Example/1234/

The time for example is completely irrelevant for me in most cases. I usually wish only to see how many tests fails if it's unstable but else I really just care SUCCESS/FAILED.

One way would be to hard code with a bit more succinct message. Another way would be to allow templating the message:

Project $PROJECT_NAME build $BUILD_NUMBER: $STATUS: $PROJECT_URL $TESTS_RESULTS