I didn't use an AI for 8 weeks of AMS 1 and 4 Andro. I *maybe* had some water retention, but that's it. Like you said, I was advised that unless you have estrogen issues, just let it roll (for these compounds anyway, like demonfox said), but have a true AI on hand just in case (I had Aromasin/Exemestane). Some Estrogen is needed for performance, libido, joints, blood lipids, etc... Also, Androvar (DHT compounds) offer some AI properties by themselves, so something to think about. I did use Inhibit-E during PCT.
But there are a few camps on when to use AI's. One that makes a lot of sense to me, but flies in the face of what is considered SOP, is to use an AI on cycle (AAS Test users do this all the time) to maximize T:E ratio, but just use a dual SERM for PCT with maybe some Cortisol control. In a nut shell - after you stop the PH cycle (we have no long esthers to worry about) your endogenous T is in the cellar - how are you going to have high estrogen? As the SERMs bring up the Test by tricking the HPTA, Aromatase starts to occur, but you are protected by the SERM. During that time, the body wants homeostasis and clears any excess Estrogen via the CYP enzymes quickly, before any Gyno could occur, and you are SERM protected anyway. (Hopefully) By the end of PCT, everything is normalized. "Estrogen Rebound" may be talked about, more than it actually occurs. Blergs and StanleyG explained it pretty well in a couple threads.