A lot of items boost more than one stat, but it often seems like the lesser boost is more for flavor than anything else.
If I have an item that’s +8 persuasive +3 shadowy, the shadowy bonus really doesn’t matter, does it? I’m not going to use it in my shadowy outfit when there are better options.
The same even goes for BDR in a lot of cases. A really good item that also has +1 BDR won’t get used if I have a +2 BDR option, and is no better than any other +1 BDR option I have for that slot.
Are there any cases where an item boosting multiple stats is actually useful?
Sometimes an item with two stats will be your best item for both stats. This isn’t often the case with +7/+2 items (of which there are a few), but there are a couple of +8/+5 items that are nifty. Such items still usually aren’t best-in-slot for the second stat, but they are cost-efficient.
There are a few cases where you need more than one stat for a single check, but they can probably be counted on one hand. Starting the Jack of Smiles case, for example, requires two stats to be 130 at the same time.
Note that for BDR, there are a few checks that are based on one of the three stats. So even if you already have a +2 Dreaded item, you will still find uses for +1 Bizarre.
BDR itself is a something where multiple stat boosts are useful. They’re 3 separate stats, remember, and notability upgrading is something that requires all 3.
There are a few cases where you have to succeed multiple stat checks at once. Off the top of my head the only one I know is gambling for a Yacht, where you have to succeed both a Persuasive and Watchful check at once.
I can only think of one Companion with multiple stat bonuses that can be relevant for ages in each category, and that’s the Fate-locked Laconic Prodigy. Molly is my Companion of choice for any number of Shadowy, Dangerous, or Watchful activities. And there is, of course the Shrine to Saint Joshua as the best Home Comfort for both Shadowy and Watchful endeavors…
There are also instances where you don’t necessarily just want the highest number possible, and having a variety of bonuses allows you to tailor your stats to what is best to the situation. The main example I can think of is when your trying to grind a stat, where you’ll gain more CP for a lower chance of success: getting an 89% chance gives you the best odds of getting 2 CP instead of 1.
It becomes relevant if you’re in an area where you are frequently playing options of two or more stats, allowing you to more easily tailor your outfit to make two kinds of checks 100% straightforward without needing to switch outfits in your Myself tab constantly.