Where to draw the line
In general, the smaller the size of our bounded contexts, the easier it becomes to manage complexity. Does that mean we should decompose our systems into as fine-grained a granularity as possible? On the other hand, having extremely fine-grained components can increase coupling among them to the extent where it becomes very hard to manage operational complexity. Hence, decomposing a system into well-factored, collaborating components can be a bit tricky, seeming to work more like an art rather than an exact science. There is no right or wrong answer here. In general, if things feel and become painful, you most likely got it more wrong than right. Here are some non-technical heuristics that might help guide this process:
