The i230 weapons will take 3 weeks worth of tomes. Sephirot ones will take a few hours worth of effort.
i170 relic weapon can be instant jumped if you had a Zodiac. Just a little effort if you go the FATE route.
i200 can be rushed for 60% of its process and the remaining 40% isnt really difficult.
i210 can be instant if you have the money for it. (and comes along with daily roulettes)

Don't really see this relic as a "grind" :|

Also, most likely the next step of the relic will be around i240.