notedeck has an interesting mode if you are crazy about privacy:

if you set up a column with a private follow list, and another column with a global firehose feed, notedeck will be smart enough to populate the private follow feed from the global feed data, without leaking your follow list to relays.

You can use this method to follow tens of thousands of people without hitting relay query limits. Since the query is only running locally, all you need to do is feed in a global query into the local relay and all of you local, private queries will still work.

This is kind of like how bitcoin works: monitor data in the p2p network and look for transactions to you without explicitly requesting it. This is great for privacy, but only works if the firehouse of notes isn’t too busy.