Second-System Effect

If

The first system is built cautiously, by someone unsure of the ground. Its success converts that caution into confidence, and every idea deferred the first time is loaded into the rewrite at once. The result is over-general, late, and frequently never ships at all.

Then

“When rewriting, carry forward the constraints and not just the wish list. Cut the deferred features to the two that actually blocked users, and replace the original one piece at a time.”

Unless

Gall's Law — the answer is not to freeze the first system but to grow it — a rewrite that ships in slices is not a second system