This week is the exprience week for Hero.
Monday to Friday is 50% experience extra.
Saturday & Sunday is 100% experience extra.
To get the maximum benefit, you may want to consider to do so.
Kill several types of monster.
Compare the experience you gained in 5 minutes time.
Select the one which the most experience gained.
It may give you .01% each kill but you may gain more if you could kill it fast.
It is less advantage to kill those monster with high experience return but take longer time to kill.
Compare it by time
Hope this help (^^)