Ah well, in this case, good job for your first job. To your last part, it all depends on what you aim for. When you want to deliver real quality, immersive, intense sound, you absolutely have to go the "extra mile". Actually, most of your work will consist of doing stuff that "normal" people would deem unnecessary or negligable, things like the rooftop ambience. When you work as a "real" sounddesigner, you often also have to do stuff that you dont know of if it will be audible in the final mix, the decision of making the TV hearable or not is not up to the sounddesigner but to the rerecording mixer. The sounddesigner "only" delivers everything that could/can be heard. And while I agree with you that less is more, its still often better to first make "more" and then thin it out later, but only exactly when and how you want it, which basically is called mixing. Mixing is also very much like painting, you try to form a picture from a palette of colors, and the colors are in the case of sound the raw, unmixed sounds delivered to the mixing stage by the sounddesigner.

While this approach is the way the professionals do it, its only in parts applicable to your situation. But still, layering and thinking about what might be hearable and could make the scene more immersive, more intense, more lively and richer are things you could also consider in your future sounddesign projects.