Navin
MALDREAD
Considering the fact that BW001 confirms he's still 10, yes less than 1 year has passed. You're time argument makes no sense and has already been disproved by canon. Nobody said time hasn't passed. In the anime-verse less than 1 year has passed not 15 years like has been erroneously stated.
Up until BW001, he seemed like he was aging. In fact, even though he wasn't growing much taller, he seemed definitely older in DP than in OS. Maybe that was the combination of his clothing making him look older and his more mature personality, however. He felt like 14/15 in DP.
But of course, BW set it clear that canon and the children keep him forever 10.
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Not to bash BW any more, but I don't think people would be asking this question if not for the 'reset.' Had the show ended in a post-DP arc, or continued with Ash winning the tourney in BW (as the next progressive step), then everyone would view Ash as a natural character that took several regions of long travel and effort to slowly but steadily reach his goal.