Which social networks you should monitor depends on your business, your audience and your budget. An enterprise business should generally have some social media presence on every platform that has users because those users are likely looking for you there; a smaller business can probably stick to core platforms like Facebook and Instagram. Different audiences will use different platforms more than others — an auto body shop doesn’t necessarily need to have a presence on TikTok (though it likely would help to stand out)!
Finally, your ability to devote resources to social media will go a long way toward deciding where you can and can’t show up. If you can build a devoted social media and customer service team to service a wide variety of platforms, do it. But if your resources are more limited, you’ll need to be more picky.