Thank you for your reply Pilou. Could you elaborate a bit more on your answer?

What do you mean by order and size of the inset?

I have used the same Inset value (1mm) for all the Insets in my examples. But I'm getting various results and I don't understand why. The expected behavior of this function is: select a face, Inset, and then get an Inset with a 90 degree angle from that face. The function works sometimes, like I have demonstrated, but it seems to fail sometimes and it's not clear why. Also I don't understand why sometimes the function is creating an Inset with some faces aligned to adjacent faces, while some are aligned correctly to the selected face.

Thanks.