Gemini and Virgo
the mind, intellect, ideas, thoughts, information, and communication of all kinds.
Per 12 Signs
About 1 year.
On average about 1 month per sign. As little as 2 weeks, but as long as 10 weeks when Mercury goes retrograde!
Mercury goes retrograde about 3 times per year for about 3-3½ weeks at a time.
Mercury goes Out of Bounds from 2 to 4 times every year.