You should, always, make the time to ensure they leave well. That they leave with a good taste in their mouth, so that they can go to their next job and will consider returning to your company in the future with the new skills they have learnt in their following career stage.

It always surprises me when companies push people out, and treat them badly upon leaving. Overwhelming them means they are likely to bad mouth and hurt the reputation of the company, and unlikely to return (which you may wish for in the future).