It depends on your definition of 'requires no more building'.
Markets and people change all the time. Because of this, there will always be something that can be improved.
Because of this, it depends on where you draw the line. I have realized that I want my products to be 'done' as soon as the MVP is shipped. Then, depending on traction I continue working on them, or focus on marketing, or move on to other products.
It depends on your definition of 'requires no more building'.
Markets and people change all the time. Because of this, there will always be something that can be improved.
Because of this, it depends on where you draw the line. I have realized that I want my products to be 'done' as soon as the MVP is shipped. Then, depending on traction I continue working on them, or focus on marketing, or move on to other products.