Constant tokio::runtime::scheduler::multi_thread::worker::MAX_LIFO_POLLS_PER_TICK

const MAX_LIFO_POLLS_PER_TICK: usize = 3;

Value picked out of thin-air. Running the LIFO slot a handful of times seems sufficient to benefit from locality. More than 3 times probably is overweighing. The value can be tuned in the future with data that shows improvements.