Well, when you think about it. . There are episodes that get split and take place time wise over only one day-but you might get two or three episodes out of it. Give or take maybe you time skip a week or two to get to the main league tournaments-ash should be 11-ish. With about 630 episodes Ash doesn't age according to years passed.
haha.... i know and there is like how many seasons?
honestly i think its because that they dont really want him to be older or the whole journey is suposed to take over a year or so ? who knows?