Here's a little demo just in case anybody else curious about rate limits. 
'use strict';
const
	SteamCommunity = require('steamcommunity'),
	SteamTotp      = require('steam-totp'),
	COMMUNITY      = new SteamCommunity();
const
	USERNAME        = '...',
	PASSWORD        = '...',
	SHARED_SECRET   = '...',
	IDENTITY_SECRET = '...',
	CODE            = SteamTotp.getAuthCode(SHARED_SECRET),
	INTERVAL        = 5000;
COMMUNITY.login({
	accountName:   USERNAME,
	password:      PASSWORD,
	twoFactorCode: CODE
}, function(err, sessionID, cookies, steamguard, oAuthToken){
	if (err) {
		console.log('login ERROR:', err);
		return;
	}
	COMMUNITY.setCookies(cookies);
	let n = 0;
	const onInterval = function () {
		n += 1;
		const time = Math.round(Date.now() / 1000);
		const key  = SteamTotp.getConfirmationKey(IDENTITY_SECRET, time, 'conf');
		COMMUNITY.getConfirmations(time, key, function (err, confirmations) {
			if (err) {
				console.log(`${n}: getConfirmations ERROR:`, err);
				return;
			}
			console.log(`${n}: getConfirmations OK`);
		});
	};
	setInterval(onInterval, INTERVAL);
	
});
INTERVAL === 10000 
1: getConfirmations OK
2: getConfirmations OK
3: getConfirmations OK
4: getConfirmations OK
5: getConfirmations OK
6: getConfirmations OK
7: getConfirmations OK
8: getConfirmations OK
9: getConfirmations OK
INTERVAL === 5000 
1: getConfirmations OK
2: getConfirmations OK
3: getConfirmations OK
4: getConfirmations OK
5: getConfirmations OK
6: getConfirmations OK
7: getConfirmations ERROR: { [Error: HTTP error 429] code: 429 }
8: getConfirmations ERROR: { [Error: HTTP error 429] code: 429 }
9: getConfirmations ERROR: { [Error: HTTP error 429] code: 429 }