While I am not expecting ANYTHING to come from this upcoming maintenance period, I would like to respond to the people who claim an update could never come so closely on the heels of a previous update. Here is some information on previous GT6 updates:
(Version, Release Date MM/DD/YYYY, Quick Summary of Update, Days Between Updates)
v1.01  12/5/2013    Brings Vision GT, Online Features, & More
v1.02  12/18/2013   Red Bull X Challenge, Login Credit Bonus & More                 
13 Days
v1.03  1/22/2014    BMW M4, the Toyota FT-1 concept, and Mario Andretti's 1948 Hudson stock car
v1.04  1/28/2014    Mercedes-Benz AMG Vision Gran Turismo Racing Series, the Corvette Stingray GT Concept '13 and two variants of the Gran Turismo Red Bull X2014                       
6 Days
v1.07  5/14/2014    Minor functionality tweaks to online mode, BMW Vision GT
v1.08  5/30/2014    Ayrton Senna Tribute Content, Mitsubishi Vision GT Car          
16 Days
v1.10  7/25/2014    Aston Martin DP-100 Vision Gran Turismo and Nissan CONCEPT 2020 Vision Gran Turismo, Brake Caliper Paint, More Car Number Customization Options and Engine brake reduction control on formula cars disabled
v1.11  8/6/2014      Improvements to mutli-monitor and open lobby                    
12 Days
v1.15  12/17/2014  Chevrolet Chaparral 2X Vision Gran Tursimo & Infiniti Vision Vision Gran Tursimo
v1.16  12/24/2014  Mazda LM55 Vision Vision Gran Tursimo                               
7 Days
The website that I took this information from stopped at v1.16.  There was also set of updates 15 days apart that I forgot to list.  So, as you can see...there are occasionally times when updates do occur fairly close to each other.
SOURCE: 
http://justinfromthesandbox.blogspot.com/2015/01/gran-turismo-6-update-history.html