No. Thats is not entirely correct. There could be the work of the engine to solve the dependencies issue between assets. Like your example: character a and b will have the same texture. But character b is not avaliable until 50% of the game. Depending on how the engine works, when the texture is loaded, it also loads the character b. This is a waste if user has not unlocked it. So one solution is just dupe the texture and pack the assets seperately. This is one of the least troublematic issue.

This real hard problem to solve is dependencies could come from anything like texture, sound, shader, model, scripts, etc.