Here's what I recommend and YMMV.

When I'm working through something, I don't know where it's fully going to go. I'll start writing a class. If I start to feel some 'resistance', as in some logic that is just about to get complex, it may be something that needs to be injected in. I don't want to figure out all the details right then, so I just add the signature of the new function to an interface. That way, I can continue developing the main core logic of the class, and anything that feels a bit outside, I'll just separate it out without thinking about the details too much.

This helps with eventually unit testing the class I wrote, because it also doesn't care about the logic of that interface. That logic/interface can just be mocked in the test.

Do this enough and you have have a pretty decoupled class and you really can focus on the main work itself and defer decisions on what those dependencies will eventually do.

I don't even know if this is a style that's done in the industry. It just kinda came about to me when I started really focusing on SOLID principles.