I have about 530 watermark in my major weapons with playing over 600 hours. It will be another 300- 400 hours at least before those weapons reach 580. And, I will quit the game if I have to do many more daily myrkgard, sirens, portal etc zergfest watermark runs. It is so boring.
There doesn’t seem to be a point to do 580 quests. Buy the faction weapons, and those should last for the months it will take to grind out watermark. In fact, by then you could just level up all your crafting and build legendary weapons. This game is forcing everyone to be crafters with the high quality items using cooldowns anyways.