Technical debt

Technical debt is the accumulated cost of implementation choices that were quicker at the time and make future changes slower. The metaphor is apt: taking it on can be entirely rational, and the interest is paid on every subsequent change.

Not all of it is carelessness. Shipping a simplification to meet a real deadline is a deliberate loan, and often the right decision. What turns it corrosive is that it is invisible on any report — the system works, the demonstration goes well, and each new feature quietly takes longer than the last.

The symptom to watch is a team that has become slower on similar work over time, or that hedges every estimate with "it depends what that touches". Paying it down is not a rewrite; it is fixing the specific places that are slowing the work you are actually doing.