The question to ask yourselves is, is it DNA? If it’s DNA that means it’s automatic, consistently being done, and everyone’s comfortable that it’s going to be done. Here’s a rule of thumb: Until it’s habit and consistent (DNA), it should probably be a Rock.
Not to pick on any one person here, but this comes up a lot when setting a sales-related Rock. The common response is, “I’m going to do that anyway.” Frankly, in my experience, most of the time it’s an excuse for not wanting to be held accountable to the expectation. Another rule of thumb: If a majority of the team wants it to be a Rock, it’s a Rock.
Simply ask yourself the following: Is it one of the three to seven most important things that must get done? If the answer is “yes” and you’re saying you’re going to do it anyway, then make it a Rock.