I just check a couple times a day... honestly, I'm usually too busy when I'm not checking HN to deal with a reply right at any given moment anyway. It's a forum.
I use hnnotify to tell me about replies and the Hacker News app on iOS by premii is pretty decent for read only access ( I mostly only post when I'm at a computer, I find that my responses make a little more sense that way :) )
Kind of wish HN would adapt Open* or similar for token access for posting... though that opens the door to a lot of potential issues (spam) I'm guessing they're trying to avoid... maybe requiring the web interface until you hit 1K karma or something.
Worrying about spam doesn't make much sense here, as the web interface is pure HTML forms, with no client-side checks. It isn't hard to automate the posting process.
Dunno, I'd be okay with web notifications via chrome.
Though that some clickbait sites are asking for that permission is really irritating... I mean more so than interstitial or late-loading ads that push content down.