For me /newest is always open. Refresh about every 1 or 2 hours if not too busy. I do go through a ton of submissions and if it's interesting or something in my field I'll go through the comments as well. I probably check over a hundred submissions a day. I've deemed it a very worthwhile use of my time, there have been countless occasions were something has come up and I remember a post from HN that points me in the right direction or has an interesting view of a problem or solution.
Newest tab, checking 3 or 4 times a day. This changed once deleted twitter and find it better / healthier. Before would check top stories once or every two days or so
I have the newest tab always opened. Refreshed in the morning and in the evening. Them I'm scrolling back :)