In general it’s not that important but there are a few considerations. There have been instances that just disappeared so that isn’t impossible. There could be instances that yours is defederated from and that would affect what content you get. Also when searching for communities you might not see things you would be interested in because nobody on your instance has searched for it yet. The first successful search for a community requires you to know the actual community address and then that causes it to federate with your home community so if you just search for a word, like cats, you will only see cat communities that someone on your server is already subscribed to or already searched for.