It would depend on the worker with me. If he was a loyal worker and not the type that was always taking advantage of us, I pretty much let them do what they want. Most are ready to go at the point they give notice. No point in having them work if they can go to work for who ever their going to now. I guess you know in your mind what kind of employee it is and have had some that I didnt see the point in having them around if they were leaving so why give them the 2 weeks if there fine leaving now.
If they are leaving tho, I pull the keys now on the ones that hadnt been with me for a long time. Cant really say I have had that big a turn over anyway on guys that have been with me long enough for me to have deceided I want them working for me. The ones I dont want that you are trying out....once I know their not a good fit, I just get rid of them. No sense of wasting their or my time.