Making a decision today that leaves you 1% worse off won’t have much impact tomorrow, because failure doesn’t happen overnight.
But as time goes by, and the small declines compound, suddenly there’s a big gap between you and the competitor who made slightly better decisions each day. This poor result is the sum of many small choices—a 1% decline here and there—that added up to a big problem.
In production it might the decision to use cheaper materials that results in dealing with greater customer complaints and returns. In IT projects it might be the decision to spend less time on requirements that results in more people, spending more time on rework. In operations it might be the decision to fix the data without addressing the underlying root cause that results in the problem happening again (and again).
Marginal gains are simple improvements, continued every day; while marginal losses are simply mistakes, repeated every day.
‘In’ is your prefix here: incorrect, inefficient, ineffectual, indecisive, inconsistent, inappropriate, insufficient, …