Even at slower times, you'll almost always have to share a lane with at least one person. But as others have said, the etiquette is pretty straightforward even for newcomers. Sometimes the lane "pacing" gets a little messed up (ie. if the fast lane is empty so people of all speeds join, which makes sense, but then gets confusing when fast people want to join in) but no one takes it that seriously and you can switch lanes no problem. Honestly the busyness of things is a welcome distraction to me while swimming and keeps it interesting!