How long do artists have to wait for renders?

Here's a question I would like to hear from everyone....

How long do artists have to wait for renders?

We have express queues for single and first-middle-last and we also have regular turn around jobs. We set priorities etc for stuff that needs to be pushed through a little faster. But how long do regular artists wait on average for their renders to return? Not including how long it actually takes to render. I'm talking about someone submitting a shot for lighting and when they expect to get it back for review? Hours? Days? Weeks?

I'd like to hear what everyone has to say :)

Thanks;

John Hickson