I'd go by usage and skier style/profile for that particular ski, over just ski waist width.
1. For groomers and groomer bias. I'd be more forgiving about it: either 1/3, .7/3 or 0.5/3 for groomer carve/bias skis, including race skis, as long as you are just using them recreationally. If the factory base bevel is at 0 or close to 0, then whichever of these you might choose. (For myself, this would be shallower bevel (say, 0.5) for slalom and slalom-like/ST skis, steeper bevel (say, 0.7) for GS/LT skis.
(The problem here is that many or most factory skis come with a 1 base bevel, and flattening that to .7 or .5 means cutting a slight slope into the base material, not just the metal edge. This in turn makes for a more forgiving, easier turning/initiating ski - which works, but with slightly less sharp carve to it. [Some, including myself, like it that way almost as much as without it, for some less race course uses and skis.] So to get the most out of the sub 1 base bevels requires premature flattening/grinding the entire base after setting the base bevel, then refreshing that bevel again after the base grind/flattening.)
What I'd recommend instead, if the base bevel is indeed at or close to 1 when you get it, is to set the bevels at 1/3 provisionally, and ski it that way until the ski feels ready for a first base grind, or until you feel ready for something different - before you go through the .7 and .5 base bevel tune/grind/tune sequence. In the interim, ski it with the slight beveling of the base material, until you get the hang of that, or just for the fun experience, and then base grind to level the bases as a result of that sub 1 base bevel. I've found that FIS GS skis in particular handle with a bit of freerider, quicker turn flair in this interim condition, able to be downright turny when that's wanted.
2. For a bump or tight tree ski. 1/1 or 1/2, depending on your pivot/carve ratio. (If you use high angles for this, hey, go even 1/3, etc.)
3. For an all mountain ski generally. 1/2 is a good happy medium - again, unless you find yourself with a lot of high angle carving everywhere.
4. There are different, legit preferences for powder and powder/crud skis, also dependent on your skiing style. Trade-offs. No one answer.
If your powder ski is a bottom or sink to the bottom carver, fat or thin, then I can see a 1/2 or 1/3 edge tune.
If it's more of a pivoting ski, and that's how you use it, then 1/1 or 1/2. (The more carve to your style, the more 1/2 or even 1/3, etc. might be best.)
If your ski is more a floater, then the bevel will not matter as much; but folks can feel the differences:
There are folks who like 1.5/1 or 1.5/2. A bit more forgiveness and looseness to laying it over.
Many like 1/1. This gives a smooth, easy carved turn that matches at least slight floating (on skis narrow to fat). For me less fun in crud.
I like it for that until it's skied off some and I want more carve through the crud.
Many like 1/2. This also fits powder and powder crud skis - in this case ones that like to carve more, and fit that style. This is what I use for both all mountain and powder boards, other than powder bottom carvers.
Some like 1/3 (or .5/3 or .7/3). If you find yourself laying it over at fairly high angles even in some powder and in powder crud, then 1/3, etc. is better, probably. On some particular carve-centric soft snow skis, 1/3 feels better to me.
Favorite skis are the iSpeed Pro and iRally.
