User blog comment:Guts!/Anime Depiction of Luffy's Gear Second/@comment-972068-20130528014001/@comment-10112860-20130528225658

 [ Thus Luffy is now able to use Gear Second for his usual fighting style without using it on his entire body     . Although the anime still has his entire body undergoing Gear Second's effects, but it still only lasts very short periods of time. ]

Also Here:  ( Luffy's Misc page )

Anime and Manga Differences
[ In the manga, post-timeskip Luffy is capable of using Gear Second maintaining it in a single part of his body, while in the anime, he shows no such difference, requiring his entire body once more to turn red and emit steam like previously. ]

THATS THE WHOLE POINT PEOPLE! Even in the wiki it is said that the depiction of anime is wrong! You just can't go against the wiki, its the source of wisdom in the world of one piece :P