Zoro's timeskip training was for the purpose of being strong enough to protect his captain (Luffy).
Oda has hammered this point in the Onigashima raid. Zoro has literally and figuratively been carrying Luffy throughout the Raid. He has been protecting him every step of the way. Some examples...
Welcome to the Fan Club of one of the most badass characters of One Piece
Jefe de Jefes :
Eiichiro Oda (尾田 栄一郎 )
@Den_Den_Mushi @Garp the Fist @ShishioIsBack @Cinera @Light D Lamperouge
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