4–8 episodes is the sweet spot. Short enough to complete, long enough to build a loyal series audience. Anything over 10 risks losing viewers before the end.
Gradually — weekly or twice-weekly releases build anticipation and give each episode time to gain traction. Binge-dropping a series rarely performs as well algorithmically.
Create a series playlist immediately, use consistent thumbnail branding, mention the series name and episode number in every title, and pin a comment linking to the full playlist.