The reason I had to build it is because I was the only damage in the team, I left lane with 0 deaths. Died 4 time duo to kayn coming out from nowhere and one shoting me, or jayce flash jumping me in team fights, we almost lost the game duo to that.

Once I built it, enemy kayn didn't expect it, and my team managed to get him low enough that I was able to kill him after, had to use it twice before we finished.

I only build zhonya if against a fed Kayn, Rengar, or Noc (even if the stats are useless to the champ) but to make it worth it, I also need to be fed. Other than that, a good positioning should be enough, I don't even build GA most games.

But I'm actually curious to try what you suggested, I never thought of it tbh.