I dont care, cos I do get paid by the hour... as long as its not my fault the drawings are wrong, then generally, I'm reasonably ok (Alright there are times where I've worked and reworked the drawings and I'm sick of the sight of them)
Sometimes they change because the client changes their mind... sometimes they change because the price has come in too high, but my job is to create and change the drawings... and that is what I do to the best of my ability
Change is part of the design process, I have learned to accept it