Elimination half-life of Femara (Letrozole) is 2 days. Therefore, 2.5mg ED may be too much and result in estrogen crash in your body, which certainly is not a risk one may want to take. Although 800mg of aromatizing test will produce quite a bit of excess estrogen in your body, you may still want to try a dosing protocol of 2.5mg EOD and see how body responds to that. Besides, Femara (Letrozole) is possibly the most effective new generation AI in terms of preventing formation of gynecomastia, so you may as well stick to the half-life dosing protocol of 2.5mg EOD.