many moons ago we tried to figure out exactly what the triggers were for free retries but I never got enough data samples to figure it out. Its not every 3 months but sure did seems so there for awhile. I'm sure it has more to do with timing of expansions, major patches, time of year, etc. Bottom line is once you've paid your $5 (or however cheap you can get it), you'll occasionally have free re-tries (historically sometimes 7 days, sometimes 10 days) to knock out whatever p2p stuff is on your wishlist. ... And use the retries when you get them because they expire.