Yeah Sand Rat Cellar is really early in the game, clearing the stage opens up the Zeklaus Desert random encounter area.,
As for splitting versus grouping depends on what type of characters you are using. Certain characters like monks have Chakra and other abilities that work based on height and close group formations. I don't like to split when using White Mages because of Shell and protect. Others like the summoner can support from a distance with spells like Golem and Moogle or a chemist due to the instant effect of potions and they only have a radii of one anyway.. Its easier to split with the way more powerful special characters than normal ones too.
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