How do I use the updates of 1.3 to produce seamlessness no matter what?

I’ve only been using 1.3 for at least three days, right now very confusing and slow and buggy

But so far, I’ve only been able to do semi-seamlessness by following some tutorials

I also have a hard time properly seeing the tileset as it should be, so I have to look twice to see which parts properly connect and such

The Aseprite 1.3 Update is a Literal Game Changer - YouTube Maybe this can help? Im guessing this is what you want to achieve.