Which brings me to my second question. If it is true that only 2.5k custom audience members can be uploaded daily, then there must be other ways to target ads better. Mainly I have been narrowing by precise interest, say 300-500k, and then segmenting by age. While I have been able to get some good feedback this way I am still targeting 70-100k segments at a time that seem pretty broad.
I am going to be trying other angles to market based of geography and interest but know I am missing a lot on how to target niches better.