I have 40 workers on hive and have 0-1% stales, check your network/servers etc. sounds like an issue or setting on your end, not hives.
And people can maliciously send stale shares and get credited 50% in addition to the valid shares, and get paid at a higher rate then what they would do valid shares alone, which is why stales are capped at 5% before manual review, to be sure they’re not being abused.