To your first point - sure, but if you're not willing to invest the one-or-two-days in the exercise why should the candidate? If you're offering a top-tier sala

To your first point - sure, but if you're not willing to invest the one-or-two-days in the exercise why should the candidate? If you're offering a top-tier salary, or something so technically exciting that it can't be resisted, then sure, you get to set the bar as high as they'll jump. Otherwise "Are we willing to invest this much" is a good rule of thumb for what you can reasonably expect of the candidate. To your second point - any hiring exercise is going to be stressful for the candidate. False negatives are better than false positives (for the hiring party). If you're certain that this is going to cost you too many good candidates, then you're going to have to find some other way to demonstrate good faith up front - offer to pay them, offer to host them on your premises, something like that.