Although it takes extra time and costs a bit more, as Glen mentioned many find one snap at each connection sufficient, I would go with the "double snap" method.
I built my first set of armor using only one snap at each end of the nylon, but 5 minutes into my very first troop my left shoulder bell and bicep connection came apart. I ended up removing ALL the strapping and replaced every single connection with 2 snaps at each end. That may have been overkill, but I now do that on all my armor, and to this day I have never had a connection fail.
Even if you don't use two snaps on the individual limb pieces, I highly recommend using 2 in the areas seen below. The pic shows the original method, but note that the straps were glued on one side. I don't suggest this. Elastic will lose it's stretching properties over time and at some point you may need to replace one or both. Hint: Note how the elastic is doubled over on the snap end below. I do 3 folds for added strength, glue the folds together and then set my snaps. The reason being is that those connections get a lot of wear and tear when suiting up/down, so better to be safe than sorry.