I honestly try to avoid AI's as much as possible. Bloods are definitely the way to go, but if my test is a little out of range I kind of expect my E2 to be a little out of range. If I'm experiencing no sides, BP is in check, mood is stable, no excess water, no gyno (I'm not gyno prone) then I leave the AI's alone and save them for blast. I may even run a blast with no AI (for instance say 300 test 350 tren 350 mast) Estrogen is important for bone and connective tissue health among other things so it makes sense to me to let those things catch up to the new strength my muscles get on blast. Just my personal method at the moment. Seems to work for me, but everyone is different.