You really only need one pack per 5 gallons, as long as its fairly fresh.
If its an older pack, you could add a bit of dry yeast to round out the sacch cell count.
If you're pitching into more than 1 container, its a good opportunity to experiment with the mixed cultures.
Use two different mixed cultures (Roselare and a lambic blend, BugFarm, individual cultures, etc),
pitch one in primary and one in secondary (after sacch ferment),
lactic fermentation in one before pitching the mixed culture,
use the Roselare in one, bottle dregs in the other,
Aerate one but not the other (I would be REALLY interested in this since I haven't done it),
etc. etc. etc.
If you mix up the fermentation of the same wort, you'll also have more flavor options to work with on the back end, eventually blending for a more complex final beer.