I was headhunted and it took relatively long until I had a phone screening with the hiring manager. I had a series of on-site interviews, a home assignment, was asked for references, they called my references, HR told me the references spoke positively about me and they will send the offer shortly, and over two weeks later they called to say they chose another candidate. They were nice and professional, but the fact that they rescinded the verbal offer after telling me to wait for the written offer for so long was unfair. I don't want my references to get "reference fatigue" so I'd rather have the reference check be the last formal step towards the offer, so I am unhappy with the fact that they got called when the company wasn't serious about hiring me.