All of the above answers are true.
Basically, use as few poly’s as you can get away with, without adversely affecting the silhouette of the object. That is true for all objects, near or far.
However, a game studio will have agreed poly count in pre-production, thus higher poly count will be awarded to hero assets.
The polycount of an individual object cannot be ascertained without consideration for the entire scene within the game.
General consensus when modeling game assets outside of an agreed game requirement (learning or to sell as game asset packs) is as mentioned, as few poly’s as you can get away with.
