@Ultibankai
The only grinding I ever did was in the Monster Arena, farming Speed Orbs from Fenrir so I could have 255 speed on each character.
With 255 Speed, Coupled with Auto-Haste on your armor, and using only quick hit, you would ensure that at most, even the fastest Dark Aeon, Shiva, and Penance, would get at most one hit in 20 or 25 of your hits. The rest was only HP management.
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"
