Most TV shows are written by staffs, so they're not actively looking for new scripts, writers, or story ideas. But that doesn't mean they never take submissions.
Be honest with yourself about your project's business model and commercial potential. Just as specific producers work on specific types of material, so do certain agents.
Joke/sketch packets should ALWAYS be up-to-date with your best topical material… nothing feels more stale than jokes about last year's news.