Just a quick note I thought might be a good thing to mention:
Unlike in movies where the director usually has the single most influence on a movie (outside of some producers who are known for their own branding of movies) - in television, the executive producers / show runners are the people who have the most influence. Often it is the executive producer's idea to begin with
Above the Executive Producers is the financer or studio who is actually paying for the show. They usually want the EP (Executive Producer) to make sure it is good on a creative level and they will sepnd more of their time making sure the show sells if it's not sold already or satisfies investor interests. The UPM (Unit Production Manager) will make sure it makes it's budget on a very nuts and bolts level.
The only director who has a tremendous amount of influence on the show is the director of the pilot. Most decisions made in the pilot affect the rest of the run of the show.
When you come on to direct a show that is already running your job is to bring your best game to the show - but also respect the existing laws of the world you're working in. How closely you need to follow them is a decision of the Show Runner.
The writers also respect the rules of the show. These rules are called The Show Bible.
Hope this was of interest.