Does subscribe("newBlockHeader",...) consistently provide the header of the most recent block?

[AlirezaEthDev]

Assuming we are trying the blow code that subscribes to incoming block headers and returns the header of the i-th block in the ledger, triggering the execution of the callback function in then(). If the callback function takes an extended period such that the (i+1)-th and (i+2)-th blocks are added to the ledger, will the subscriber receive the header of the (i+1)-th or (i+2)-th block for subscription? Does it consistently provide the header of the most recent block?

web3.eth.subscribe("newBlockHeaders",function(error,result){
    if(error){
        throw error;
    }else{
        console.info("Result:\n"+result);
    }
}).then(function(subscription){
    subscription.on("data",function(blockHeader){
...
       })
})