In the UK, a series still averages around 6-8 episodes, rarely getting into double-figures. Years ago an entire series could go by with barely anyone watching, but the channel would commission a second series on merit (usually the BBC, because that's an advantage of a broadcaster subsidised by the public). I think that happened to Fawlty Towers, which is now widely considered the gold standard of sitcoms. All 12 episodes. Barely half a season for the US.