There are no mistakes. It does come down to what a player likes or what fits their play style.
Be sure to slot the toggle powers with endurance reduction as well. Maybe add a couple endurance modifications to Stamina. (click image below for examples)
When starting to utilize Invention Origin Enhancement in melee attacks, There are popular sets like Crushing Impact, Touch of Death and Mako's Bite. Unlike common IO enhancements that boost one stat (Accuracy or Damage), Invention Origin sets can boost multiple stats.
For example using 2 Touch of Death enhancements we can boost 3 stats.
Touch of Death: Accuracy/Damage
Touch of Death: Accuracy/Damage/Endurance
A little more boosting using less slots can really add up.
On top of that, Invention Origin Sets also offer Set Bonuses which apply to all of a character's powers. Pounding Slugfest for example is available at levels 15-30 and adds 8% Regeneration, some defense and 2% Damage. Bonuses from various sets can accumulate 8% regen x 5 = 40% regen.
Here is some links to additional information: For Touch of Death https://paragonwiki.com/wiki/Touch_of_Death, Paragon Wiki Enhancements https://paragonwiki.com/wiki/Enhancement_Sets.
@Sovera note: the 'best' farmer may not even be a brute.