In the early stages of interviewing for a web UX/UI developer position, I've been informed there will be a "development exercise" which is to be completed over 48 hours and returned to the company. I don't know what the exercise is but I was told I could spend as little or as much time as I wanted on the project; obviously more effort would be more impressive.
I've taken small tests during interviews in the past, but two days of work seems somewhat substantial and unusual, so I'm curious: Is this a common practice? Are there any concerns I should be aware of? ...for example: who owns what I produce? (First-hand anecdotal answers are OK, but links to any stats would be awesome.)