Depends on the work. If it's your typical web app implementing some business requirements, then there's no deep work required - it's just talking to the requirements source and converting that into code, as per the chosen web framework. On the other hand, if the work is technical (say, you're working on a new kernel scheduler or a new voxel engine), then being left alone for weeks or months is perfectly reasonable. For example (from what I've read), that's how kernel engineers at Microsoft are expected to work.