This time last year, Netflix was known for Orange is the New Black and House of Cards. This year, it's releasing a number of new series, some of which are incredibly short. Whilst I like that Netflix is making new series, making 6 episodes of a Miranda Sings show doesn't equal progress, it equals gimmick.
No, I don't think Netflix needs to slow down as long as it has a sound business and financial plan. New ventures need funding. If Netflix is spending more now on making new series but believes it will make up the loss in the long run and make even bigger profits from these new films, then it's probably on the right track.
Netflix being $3billion in debt is no reason to slow down as long as this initial debt will be paid in full and increasing profits is possible based on their efforts. It is common for companies to become in debt in order to grow the business and position themselves for further growth.
No, Netflix shouldn't slow down because they're the most popular streaming service around. If Netflix was just starting out, the answer would be they should slow down. Netflix has many of the most popular series and movies out there. They are betting on themselves and there is nothing wrong with that. They will more than likely make that money back and much more.