This type of thinking is truly essential to forming a well-rounded professional opinion when designing or developing things that provide business value to your client/stakeholder. In some cases business value also translates to why the hell they should hire you in the first place. Consider this kind of scenario:
You are tasked with creating a new layout/UI for a web-based online game (general topic: golf, relates to real golf stats). So to summarize it’s an in-browser web app that deals with golf and golf stats.
Assuming you have all kinds of design experience, but know nothing about web games or golf, one might wonder how you could possibly have the necessary context to deliver the right experience your client wants. It is at this point in the story that the designer (you) would then conduct research on those unfamiliar topics in order to become appropriately knowledgable.
So turn you might ask: How could I be more effective on all of my projects and do less one-off research?
My personal advice here is to look at the types of clients you have (and want to have) and consider the core principles that these clients have in common. Figure out what business goals and objectives these companies share, then start thinking about the things you can learn to help you better understand what it takes to fulfill those objectives.
Here’s an example: Say you are just starting out as a designer and find yourself often having to deal with a client who has retained your services in an effort to increase conversions for one of their struggling web properties. So now you decide to read up on UX theory associated with conversions, the psychology that goes into making choices, as well as color and shape theory for effective call-to-action elements (buttons, links, etc). You expand your knowledge so that in addition to knowing how to technically design things, you understand the subtleties of implementing an effective design in context.
Just like collecting and displaying pieces of art, the placement matters just as much as the aesthetic value of the art being placed. You want to maximize the effectiveness of each piece while considering the pieces adjacent to it in order to plan a cohesive layout or pattern for your display.
It’s no longer enough to be a designer and confine your expertise to just photoshop/sketch or something similar. Having a broad understanding of not just your world, but your client’s world, will be a differentiator for anyone trying to stand out from the pack. Plus, it’s just the smart play: be the best you can be and don’t suck at your job. That’s the type of attitude people want to pay for.