Consider the orbits of Mercury and the Earth. Mercury makes a complete revolution of the sun once as the Earth makes 87.9691 rotations on its axis. A particular event occurs on Earth, and then an apparently related event occurs later on. Computing the number of days between the events shows an apparent synchronicity between that number and a multiple of the number of days it takes Mercury to go around the Sun (for example, 1:1, 1:2, 1:4). But due to the different orbital velocities, the position of Mercury with respect to the Earth has no such correlation.
Even if events happen precisely (say) 351.8764 days apart, which is the length of time it takes Mercury to make four complete revolutions around the sun, the Earth has also moved in that time, so things are no longer in the same alignment as when the initial event occurred.
About the only time you could even hint that Mercury might have an effect on events on Earth is when they are aligned, either on the same side of the Sun or the opposite, or perhaps at 90 degree angles. But those events don't happen on 87 or 365 day periods, because both planets are in motion.
Use a planetarium program to position yourself over the Sun's North pole, then watch as Mercury and the Earth orbit. I did that myself, and by using a straightedge to determine when the Sun, Mercury, and Earth were all in a straight line, came up with the following dates:
* 26 Nov 2008
* 28 Jan 2009 (55 days later)
* 20 March 2009 (69 days later)
* 18 May 2009 (49 days later)