> I think you skipped over the commenter's main point while replying to them: you need to be able to have a good mental model of the code.

I actually addressed the root cause of the main point: a misunderstanding of the purpose of interfaces in Go. To me these complaints are analogous to someone saying that they're not able to move fast enough while trying to run underwater. Why don't you try swimming? The fact that whenever a complainer elaborates a bit, it often points to indications that they might be looking for Java in Go, also leads me to connect the original difficulty to the latter misunderstanding.

> A few well defined interfaces have the advantage of being easy to understand and see usages around the codebase without the overhead of many different variants of an interface.

Interfaces in Go are not a thing. They're a notice from a consumer to say "I'll be using these methods on whatever object you pass in this slot". Not much more. They're closely tied to the consumer (or a closely related set of consumers, if you don't want to be too zealous). It's a different mental model, but if you embrace it, it changes the way you write, read, and think about code.

> I've found it much more difficult to get my IDE to point out all the different ways some interface could be implemented.

Implemented? Forget that word completely. Ask instead "does the object I'm about to send have all the required methods?" If not, add the missing ones. That's it. It's all about the methods. Forget the interface itself, it's a label on a piece of napkin, a tag, to list the set of methods required by the consumer on a particular dependency.

I think Python duck-typing philosophy is a much better access door to Go's interfaces than Java interfaces. You just care about how a dependency will be used by its consumer. Now, if as a language designer you wanted to add the discipline of static typing on top of duck-typing, the logical conclusion would be either a syntax for "anonymous" interfaces that lets you duck-type

    func Consumer(obj interface{doThis(str), doThat(int)}) { 
        obj.doThis('foo');
        obj.doThat(123);
    }