beating a boss in 20 seconds before mechanics even kick in regardless of a time limit is a horrible design. It defeats the purpose of bosses even having mechanics and this counts for any boss not just the guantlet.
It trivializes encounters and its content. Them not taking into consideration the most used gear set which has been facerolling content since day 1 when making future design bosses is the same as putting a boss with a loot pinata.
They are giving out the message, just roll zerker and you don't have to worry about things. I haven't found a reason to not go berserker.