Function effective_interval_secs 

pub fn effective_interval_secs(
    own_declared: u32,
    remote_declared: Option<u32>,
) -> u32

A sender’s effective interval (seconds) — the minimum spacing it must honor for its own data messages (SPEC §6.2): max(own declared, remote declared once known, PEX_MIN_INTERVAL). The remote’s declaration is a floor (“don’t tell me more often than this”) once its handshake arrives.