Question for FoxFarm product users

I am growing under 600watt MH/HPS in Pro-mix ( 5 gal. containers) and using FoxFarm trio. I see, according to their feeding schedule that they recommend flushing every 4 weeks. Is that necessary? Should I follow that schedule?
I would like to hear from others that use FoxFarm and see if they see the need to flush and how often!

Thanks!

I use ff i dont flush till 2 weeks b4 harvest. Just feed every other watering
Ps if ur using the trio i would get the beastie bloomz at the very least trust me it will make all the diffrence.happy growing good luck

Thanks for responding!! Do you flush with water or Sledgehammer (or something similiar??) I do plan on trying Open Sesame as well as Beastie Bloomz. Never tried them before. Are you also growing in Pro-Mix?