The essence of it is that timing and context really matter when making dialogue picks. Most conversation choices around 98% just change up the immediate back-and-forth, but there are specific moments where your calls make a huge difference. During that "search and destroy" mission, for example, choosing to save takemura completely opens up a different ending path which is pretty crucial if you're going for that route.

Life paths give you some extra dialogue options here and there but don't expect them to totally reshape the main story - they mostly add flavor and sometimes unlock alternate approaches to situations. Where things get really interesting is in those key story moments, especially anything involving johnny or decisions in the final mission, since those directly impact which endings you can access. The newer dlc content actually takes this further, with some pretty major choices around songbird that you can't take back.

Good to know that while most choices won't drastically change the overall world state, the game does remember certain decisions that affect relationships and available outcomes. It's kind of like keeping track of friendship scores in the background - treat johnny one way consistently, and you'll see those choices add up when it matters. Just keep in mind that the real heavy hitting decisions tend to cluster around those major story beats, particularly toward the end, so save those dialogue quick-saves for when you're dealing with the main players.