I take 10 mg (multivitamin) in the morning, 15 mg lunchtime and 30 mg before i sleep. Thats 55 mg, for me its not a problem. The benefits i have experienced is increased sexdrive (testosterone), better healing abilities, great skin, no acne for example.
In my experience i believe zinc is the best supplement for PE ( In my case ). I wish i had known about this in my earlier years. (You have to try and see what works for you. 55 mg may be to much for some)