On 400mg of test, proviron would be sufficient anti-e effect for most people.. however, some people have a high rate of aromatisation and may need something more. I typically stay away from anti-e as much as possible(they will slightly hinder gains), but DO make sure your estrogen doesn't get out of control... Another reason to avoid overuse is that most(arimidex and letrozole) will increase lipids DRAMATICALLY!! Aromasin is somewhat of an exception as far as aromatase inhibitors go, it's much easier on lipids! Also, blocking estrogen rather than using an ai(with tamoxifen, Clomid, etc) can help prevent e2 sides without inhibiting gains and screwing with lipids, while also helping aesthetically, as far as keeping water retention down, and increased appearance of 'hardness'... Another reason to block, rather than eliminate nearly completely, e2 is that most people will have negative sexual sides when e2 levels plummet too much. Blocking e2 WILL lower whole body levels slightly because it is eliminated at a slightly higher rate due to your body 'seeing' a 'higher' level, because more gets kicked to the bloodstream as it's knocked off the receptor and/or shbg.. (this is one of the mechanisms by which proviron helps as an anti-e(by displacing from shbg)..
Post cycle is a good time to run anti-e(both aromatase inhibitors and estrogen blockers)in order to iincrease the release of lh and fsh, in order to increase natural production of testosterone