It's the classical problem of a standard that nobody actually follows. Every UEFI firmware that I have come across has behaved differently.

My current laptop has an UEFI implementation that only boots from a hardcoded path in the EFI partition. You guessed right, the path of the windows 8 bootloader.

The UEFI in my home server overwrites the UEFI boot manager list every time you save & exit the configuration tool.

If I remember correctly, the UEFI implementation of a MBP that my friend and I tried to make dual boot Ubuntu required a blessed HFS boot partition for every OS.