It is all preference, so think about it from the perspective of users, and balance that with how difficult it is to produce, and how much the details stray from the road.
I have used GTFS extensively, and know that these details help with things like estimating how fast a vehicle is scheduled to travel (comparing it to a real-time tracking feed), or when it is going to arrive (scheduled time and distance remaining, with the distance being determined by the shape). However, it is a balance, as clearly it is a burden on you to digitise these details, and to maintain them, and at the scale of the image above, they wouldn't make an enormous difference. I have worked with GTFS shapes that are just straight lines between stops. They're not nice to work with. As long as you at least make a good attempt at following a reference road dataset, you are unlikely to hear complaints.
Most users will only be aware of the shapes when they appear on their (Google) map. If this will help someone find the correct place to wait for a bus, then definitely do it. These kinds of users are also going to benefit from the improved detail in the shapes in third party applications that use the shape for things like estimating time of arrival, assuming some of these "details" are more than minor.