Your friend is wrong. You should ALWAYS manage e2. By the time you get gyno do you have any idea the amount of unhealthy effects estrogen has been doing to you physically? Gyno is actually not nearly as serious as many of the effects of elevated estrogen. Keep e2 within clinically normal levels even when on cycle. This will allow you the positive effects of estrogen without the negative ones.
That being said it isnt always easy to manage estrogen off of how you feel. Yes there are symptoms of high and low e2 that can be felt, but there are many that cannot. Low e2 is very unhealthy as well. You really should strive to do mid cycle blood work just to check out your e2 levels. Adjust ai dosage if needed. If blood work every cycle isnt possible for whatever reason then so be it, but if you can get it a few times on a few cycles you will have a very good idea of your approximate needed ai dose for future cycles. You can use previous on cycle blood work, correlate it with the symptoms that you were feeling and you can learn your body giving you a fairly accurate ai dosage depending on the amounts of aromatizable steroids you are taking.. This knowledge will stay with you blood work or not so even if you can just do it for a few cycles the knowledge & experience you will have forever.