It took Nintendo 6 months to remaster Wind Waker in HD

[Barozi]

Frequency said:

Announced 23rd of jan, released october 4th.
At the time of announcement the game was already in a presentable state to show it off for the announcement, so what we are looking at is a minimum of 9 months from announcement to release, if they claim 6 months total to develop and we assume that the game was roughly half done when announced, that still leaves 6 months between completion and release, so you really have to wonder just why the hell Nintendo are dragging their heels so much for a console that is starved of games.

Could be that they had something else to work on within that time space. That's something we can't ever find out unless they tell us.
Or they finished it several months ago and just waited for a pre-holiday release instead of a Summer release.