I came across a concept of tear drop connection into PCB TH vias. It is a way to increase the PCB yield since even if the drilled hole is further from the required position for the TH via, the tear drop shape will reduce chance of the track having no contact with the TH via.
I looked at a few FPGA development boards that I possess. However, I could not find any tear drop shaped vias on the top or bottom layers. I am not sure if this is because the tracks are too thin and a tear drop would be too small to identify by the eye or they are simply not used. In any case, I am quite sure that I have understood the layout correctly in that no tear drop shaped TH vias are used in the PCB.
Is there a reason that tear drop shaped via connections are not mandatory for TH vias? Also, are teardrop shaped via connections also relevant to microvias?