Shortest time on a tier
 

At the end of January, I was demoted from Silver to Blue, missed requalification by 3000 odd miles. On 27 January I took the outbound of a F Saver trip CPT/LGW so on 28 Jan I got the email to tell me I was now Silver. On 18 Feb, I flew the return, again in F and three hours after landing in CPT there was an email congratulating me on achieving Gold.
So that was 28 days as Blue, followed by 21 days as Silver. Meteoric rise? Who has been on a tier for less than 21 days?

(now I need to fly 50000 miles before 28/2/2019 to maintain Gold, which is only going to happen if a few F savers come my way. nest trip is on J savers, that's only 15000....:( )

I briefly lost gold once. It was a horrible 2 months. (Remember AU golds get QF benefits on domestic flights).

I think I did 6 or 7 days as a Silver a couple of years ago. Was demoted at the end of the month then re-instated on the 13 month look-back following a flight a week or so later. I do regularly let Gold expire for a longer period, so this was an exception for me.

Been Gold for a several years now as have been commuting UK-Japan. Renewal is October, but there have been times when Gold would have expired on renewal but due to be reinstated with December flight under 13 month rolling qualification system. (The December ticket is usually booked August or September.) Whenever expiry has been due to happen I've received an email from Emirates about a month before Gold expiration to say that Gold membership had been extended until the end of December.