I’ve been attempting to time 6’s and higher while at 603 ilvl and let me tell you it’s going horribly. Should I scream nerfs like a nerd or drink a glass of git gud!? “Skill issue” 
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On a serious note I am almost 1600 ilvl hope everyone is having fun!
If you are 1600 ilvl you should be soloing 6s and probably should also be banned for hacking.
603 is low. In the current talent system, every ilvl and itemization gives you massive, massive returns. We don’t live in the Dragonflight era of trivial dungeons anymore. +5s are difficult, and +7s are brutal.
Use your defensive cooldowns where you can, find spaces in fights to pop AMZ, help your healer, and on the last boss of Grim Batol, you want to pop Icebound+Deathcharger and clear out tentacles prior to the second shadow storm so the group has room.