In onepiece, characters develop even when they are not present in many chapters. The timeskip was very interesting because all of the side characters had also developed in interesting ways. You get the feeling a lot has happened in the two year timeskip, and it's implied by 1-2 pages showing things like
Kishi writes a timeskip and only sasuke improves noticeably, every other character is at the same level as before. gaara also improves but not significantly. That's only two characters. Nothing really happens in that time either, other than gaara becoming kage-level. No one does anything interesting or makes any plans. There aren't any new relationships or friendships either: it's like everyone was in stasis for 3 years. A few other rank changes happen but they are pretty trivial. What a boring time-skip.