Item Balance VS Champion Balance

A while back before Warwick got nerfed due to the introduction of Skirmisher's Sabre, we learned that the simple introduction of a new mechanic or item can easily push a champion that was just pretty good, to a whole new level of being over-the-top in what they can bring to the field. The same thing is happening on the PBE with Sona right now in regards to her Power Chord damage percent nerf which is mostly influenced by Lich Bane being the third most purchased item in the game for her. A long time ago, and some people are probably going to get annoyed with this mention, but during Season 3 Garen received a nerf to his Passive to tone down his overall bulk throughout the game due to Defensive Itemization being exceptionally strong. I'm sure there's many other examples that could be mentioned in this thread, and add them in if you want to, but there's two questions I want input on, one which shall be a poll.

If a Champion is nerfed due to an item being too good on them, and the item in question is eventually removed from the game or nerfed to a state where the original Champion nerf itself is unjustified, should the original nerfs applied to champions because of the item be reviewed for potential reversion or left the same?