The Division 2 currently drops three seasons per year, each lasting for just over four months, giving its players ample opportunity to complete the Manhunt, the season pass and all the other events that drop throughout. Not to mention, getting their hands on the latest exotics, gear sets and named items.
Year 6 is just beginning, and the first season is slated to be the last before we start to see significant changes and new content. The seasonal model is slated to be updated for Season 2, with the long-awaited Brooklyn DLC coming in Season 3. For now, things are essentially following the current pattern, but the story is continuing to grow and Project Resolve is almost at an end.