A systems approach is a boon when dealing with decisions that are needed on an urgent basis. Urgency often requires people to rush through thought processes and skip necessary steps or tasks. Rushing through and forgetting something while making a decision can lead to an uninformed decision. This is why a systems approach is a boon.
I think it does in that is instills a level of calm with everyone involved. If you panic, you will lose no matter what, and panic is a very unstable human emotion, prone to come out suddenly and spread like an infectious disease. A billion problems you never dreamed could occur will happen and you're not going to be able to wing those problems out of thin air.
I think that it is a good thing to have a systems approach when you need to make a choice on an urgent basis, since it will make sure that you think the decision through and you will make the one that is the best and will help you out.
I do not believe having a systems approach to a problem is an indication that it has to take more time when considering something on an urgent basis. I think the most important part of the systems approach is the fact that you use the time available to consider the options, rather than simply guess.
While one may get short term positive results from systems decision making, the process implies big data analysis and scanning larger trends, which is all predicated upon the unstable high tech world that we live in. So within such a context, there may be examples of benefit, the whole system is bound to fall apart. In fact, systems analysis of the climate system is showing that the very system we are using to do our analysis is doomed due to our lack of action in the face of an urgent problem. We are paralyzed by data which we cherry pick for feel good results, and are further addicted to an unworkable paradigm.