The latter. We always report West Seattle projects as soon as they are announced. For example, the California SW work that is under way this week was announced by SDOT last week. MAJOR projects, like the continuing yearlong Delridge repaving, are announced further in advance, and tend to be distinct city budget items, but the block-at-a-time ones you see more often are, SDOT has told me re: past inquiries, added when money/crew time becomes available.
Are you wondering about a specific stretch of road?
-TR