I'm looking for a word to describe the cost, work, energy, or effort that can be lost when something is done in separate iterations as opposed to as one singular task.
For example, if a carpenter builds a house and then, upon completion, decides to add a garage, the total amount of work required will be more than if the carpenter planned to build the house and the garage and constructed the whole with both in mind.
My immediate purpose is to tell a client that we can build the "back end" of a product now and build the "front end" later without losing any work / cost / effort (However, my interest in this word is not limited to this particular client).
I would be open to either a noun or a modifier describing the effort or cost that is lost.
We can build the back end now, and we can always add a front end later without any ________.
If we want a garage, we should include it in the building plans, because if we decide to add it later we'll incur ________ cost.
I considered the words "redundant" and "duplicated," but these are not completely accurate, as the work that is lost by doing something in iterations is not necessarily lost to redundancy or duplication; it could be lost as a result of an architecture framed around the initial task not optimally suited to the subsequent task.