High xintensity only work on some pools. Pools that pay for stale shares. 2miners.com, miningpoolhub, nanopool, f2pool and many others.
High intensity with tweak might reduce the stales.


You can try 2miners.com with --xintensity 4096, and get 100% accepted shares and few stales poolside, but on flexpool, ethermine, crazypool.  ~5% stales and lower payouts.