 The disadvantage is that over time this approach tends to converge on a solution (local optimum), not necessarily the best solution (global optimum) that might have been reached if a company starts from scratch instead of building each step on the previous one.Another disadvantage is that although this solution tends to favor smaller, more incremental changes, there is often a larger up front cost to setting up all the measurement systems and staffing a company with the right analysts and change processes to react to these tests in a timely and effective manner.As a result, companies often adopt a mix of big bang efforts augmented by some smaller, more iterative efforts as part of their overall strategy.