Main Scenario Side Quests

I created 3 characters, so I can see the main scenarios in all 3 cities. Now I noticed that when I handed in one of the main scenario quests, side quests became available, and I realized that there are apparently also side quests that are only available to you if you picked that area as your starting area. So my character who started in Gridania can not only not do the main scenario quests for Ul'dah and Limsa, but he also can't do some of the side quests there.

I was just wondering how far that goes? Because the main scenarios converge around level 15. So for each region that involves around 2 zones. Do later zones, like let's say around level 30-50, also feature side quests that are only available to the characters who started in that region?

I'd love to do all of those quests, just wondering how far I have to level up my alts in order to see everything in every region, because I mainly wanted to focus on my main, and do all quests with him.

It doesn't go further after the point that they converge, then it's just same quests for everybody regardless of starting city for the rest of the game.

Thanks for the help.