I think in general, game development tends to always stretch out longer than anticipated. In my opinion, the delay will definitely be worth it, as otherwise you'll be getting something which is less enjoyable. I've done some preliminary testing and discussed various plot points with Bt, and the additional details he has added so far really help to keep the story moving and keep you engaged.
And yes, most of us are doing this in our spare time, and some of us have more spare time than others. But progress in terms of sheer volume of resources has definitely been faster than during development of KQ3 or SQ2 remakes. QFI is quite a lot bigger than these even when just talking about the art!
I will also add that with each additional piece of art, it needs to be programmed in along with additional writing. The parts of any game which are the most work are programming and animation. Programming is hard because it is all about the detail, and implementing a lot of things which people often take for granted when they play a game
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