Tyrion and Dany's arcs might not have been the most exciting, but their actions have been narrated from the start of the series and they are two of the cornerstones of the series - it makes sense that Martin would wanna detail everything that happens to them.
That's true, but usually we don't get so much all in one place like that. Look at Ned's chapters in A Game of Thrones - we get a couple in Winterfell, a couple for the journey, a few for the main action in King's Landing, and one or two in prison at the end. Most of those chapters cover other main characters too. There's no reason Tyrion's journey couldn't have been done in half the number of chapters (even a quarter the number of chapters...), likewise Dany's struggles in Meereen. GRRM could've even kept their number of chapters the same if he really wanted, and had them go way further into the future than they do.
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All the stars in the sky are waiting for you.