Treed is a work-in-progress Mastodon client which aims to be less addictive. While it's still missing some key features, it's already the client of choice of its author.
Instead of displaying all toots in a single feed, it has separate pages for each day, and it groups all the toots by the same author. Thanks to this, you can see the rare toots from your most important friends, no matter how much other people shitpost. Goodbye, scrolling through the entire feed out of FOMO.
When you launch the client, you first see the toots from the previous day. In other words, by default the page updates only once per day. Obviously, you can still just navigate to the current day and see the current updates - but only when you actualy want to. In my experience, that has completely stopped my urge to constantly check Mastodon for updates. Opening treed once per day is good enough for me. In fact, because browsing past toots is much easier than on feed-based clients, it works well even if I only check it every couple of days.