Breaking the Rut

I've been happily churning out earrings every time I sit and bead. Earrings are fast and fun so they appeal to my ADD. But women do not live by earrings alone, so I had to break out of my happy place and work on something besides earrings. Luckily, I had Swarovski glass pearls, and who can't create when they sit in front of Swarovski?

My problem, I've found though, is making two strands work with the lengths. Do any of y'all have that problem? I have the bead board with the measures, but I still seem to always make one strand too long or too short. This piece had to be corrected before it could be labeled "finished."

Multi-strand necklaces are my achilles heel. What's yours?