They very likely took that into account. This is a design tradeoff. The few times I tried VR headsets I have to say that I was annoyed by the adjustments and

They very likely took that into account. This is a design tradeoff. The few times I tried VR headsets I have to say that I was annoyed by the adjustments and the cheap/weak materials that was used, also I noticed some drift after a very short time (likely due to wear for a demo headset, but still) Not sure if custom made is necessary, but like with any eye wear, the correct size and alignment should probably be built into the device itself, it is more practical and durable.