largely the same (also have twitter and facebook blocked in hosts file, if I want to check them I use my phone, it's less convenient so I end up spending less time on either).
I think it's because HN only has "one" frontpage which changes relatively slowly rather than each subreddit I track, some of which change very rapidly.
Also half the stuff on the frontpage isn't relevant or isn't something I'm interested in so I tend not to disappear down the rabbit hole so much.
Same here. My old job had a very feast or famine tempo which ended up with me getting stuck in a nasty facebook + reddit + arstechnica feedback loop between the feasts.
Blocking all 3 via /etc/hosts broke any interest I had in FB and Ars but I eventually added Reddit back to the list permanently.