I find it trades with the coins that are moving the most, and waiting on coins that aren't moving. I had .7 btc, and had 5 pairs set to .2 btc to use. Either the first few sets get it, or it waits for others to sell. Sometimes I have a pair or two that aren't buying for awhile, and I still have .3 btc waiting for something to use it.

I wouldn't recommend having all pairs use the full 1 btc... the other pairs would be useless to have at times, and you could be sitting on that 1 btc waiting for that one pair it bought to get the profit, meanwhile something could have made 10% but it didn't have any btc to do anything.