For beginners I'd tend to say just pick something you can do in good form. For more advanced guys I'd expect them to know their 1RM or have a good guess, so 90% will do. Once you have chosen your lifts and have a session or two under your belt you should be pushing for PRs every time you hit that gym.
It should be treated differently from frequent lifting routines, in that because it's once a week you can flirt with your absolute max or close without as much of a need to hold back. I find that's why this is probably a nice intermediate step toward the more advanced routines which inevitably slim down the number of exercises to very few. You can have a good variety of exercises and figure out which benefit you, on top of that you don't have to worry as much about holding back.
I like this for intermediates, as a beginner doing full body routines you're honing your form. Here you hone that killer instinct with multiple heavy singles. Later on you'll need to periodise but by then you would have at least exhausted linear progression and have experience of maintaining control under limit weights.