Constant zebra_rpc::sync::POLL_DELAY

const POLL_DELAY: Duration;

How long to wait between calls to getbestblockheightandhash when it:

• Returns an error, or
• Returns the block hash of a block that the read state already contains, (so that there’s nothing for the syncer to do except wait for the next chain tip change).

See the TrustedChainSync::wait_for_chain_tip_change() method documentation for more information.