It’s more of a tough decision on if/when you should add an AI to the mix than actually most agree on. Yes, 80 for an e2 level is rather higher than needed or wanted. Based on you stating that you have for sure over a 15% BF level, taking an AI is not the end of the world. Some are dead set against AI’s though and there will be arguments between both Aromasin & Arimidex, along with how much to experiment with to not crash your e2.
You just have to decide which one you’d like to run and that will determine frequency. Generally, Arimidex is 2x/week and Aromasin varies on every other day, every 3 days, etc.