They know that the most time-consuming step in the process is not making the decision but putting it into effect. Unless a decision has “degenerated into work” it is not a decision; it is at best a good intention. This means that, while the effective decision itself is based on the highest level of conceptual understanding, the action to carry it out should be as close as possible to the working level and as simple as possible.
Tony Robbins said the same thing. It's not a decision unless you act (i.e. follow through).
Also implied here is that although to make a decision doesn't take long, it's the most important part when it comes to time usage. A hastily made bad decision saves a little time, but the execution of that bad decision will waste a whole lot more. Keep in mind it will probably involve others as well, wasting their time too. This is a good case for making unhurried decisions. Don't be in such a rush to act.