What is best – a storyline throughout the series or individually contained episodes?
There is no simple answer to that question as broadcasters wax and wane on the issue of whether a narrative throughline will keep viewers watching versus having individual episodes (e.g. Men Behaving Badly, Only Fools and Horses, The Simpsons) which can be dropped into the schedules at any time. Their problem not yours. Your issue is to write what you think fits. Keep to your vision.