I would suggest that a goal is always a good thing, along with a benchmark that tells you where you're starting from and a system to measure with. You might, if you were setting a goal, also want to have a sense of what we'll call legitimate ways of reaching the goal, so that you avoid costs being shifted or off-loaded onto other ledgers or accounts to suggest that the savings have been made when in fact they haven't.
Those would all be things you would want to build into the analysis.