senior developers don't stop at just one patch in the area. they send patches from one area in dozens, each building over the previous, or maybe not. this might be because they notice problems as they go over the code and then as a consequence end up writing a lot of patches to fix those.
simply put, be interested in the code around the change, don't just be focused on fixing the issue at hand and you would build insights over time. an easy way is to zoom out at the mental model of the code you just worked on, and push the boundaries of that model just a little beyond the known region.