It's sort of really dependent on what people want out of you, which has to be taken on a case-by-case basis. Sometimes people just want someone to vent at, or, they want someone to kind of be like "hey that sucks sorry about that", and actually care about them and their hardships (these are usually the situations in which people are facing some sort of inevitable problem that they have the solution for, but the only solution sucks), what they need is emotional support, and probably a boost to their ego. And then sometimes people have been like, facing what's an unsolvable problem, and they just need kind of a new, fresh pair of eyes on it. The latter is the circumstance in which people will be more open to obvious solutions, because sometimes people just won't think of them for whatever reason, could even be as simple as just forgetting that something existed. I think, in either case, it's usually a decent idea to ask obvious questions, and if you end up stepping on a bombshell ("well I ALREADY THOUGHT of THAT!"), that's usually more of a like, that's indicative of something that you both have to defuse in the moment, but that's also something that you can sort of question why that was placed there, and what the foundation of it was. Usually, though, that's something you reserve for later.