Yea, with our zine, we sometimes get over 1,000 individual pieces in a reading period for a max of 15 - 20 slots in an issue. Excluding the ones that are objectively lacking in technique no matter how you read them, 95% of decline decisions are because we ran out of space or the style / topic wouldn't mesh with the issue. Or an editor just wasn't feeling it and there's no way around personal taste, you know?