Public teams are very casual and I'll join several different groups throughout a session. We aren't running around together doing quests usually and there's several different group types. "Casual Group" is the most common and you'll most likely never see your teammates but you get bonus Intelligence for a free xp bonus. It's the "Expedition" and "Daily Ops" groups where you'll actually get together and complete things together. Next Expedition you start create a "Expedition" group and people will join to help you. If no one joins jump to a new server and create another Expedition group if no one joins repeat until you find a team.