Add those mount hole folks!

It’s such a small thing to add and yet it’s forgotten.

All PCB must have some way of mounting the board inside an enclosure. In cases where the PCB has castellated edges and is soldered to another board. In this case the mount holes can be ignored.

Other than that I don’t see a place where a mount hole might not be needed.

Even if the PCB is attached with a motherboard, ideally, you need to secure it with a screw to the motherboard. Relying just on the connector is never a good idea. The connectors are for electrical connection not mechanical stability.

It is a small thing to miss, add your mount holes weather you put it in an enclosure or not.