they could easily add say.. ninjutsu casting time -X% as a new merit catagory, this would solve many issues here. and w/ utsusemi probably near the cap with proper gear already, it could be balanced very effectively. or add a static - casting time to yonin/innin ( or a JT)

i dont see spells comin in ni form due to the ability to cast in succession, same reason its unlijely we'll ever see utsusemi: san. if you could cast the current ichi spells in 1/4th the time with proper gear/merits, would you? would it give you more incentive to cast them?