Sexdriven
Simple. If you're exhausted, it's much safer on one engine cause everything happens....t h a t .......m u c h.....s l o w e r. This gives you have more time to react and in case you screw it up, you end up in the terminal building with less velocity! However, I always insist the F/O's use full reverse. The noise usually wakes me from my micro sleep just in time to handle the radio.
Nowdays, I'm even contemplating shutting one down around 2000' on finals. Not only should this save fuel and make the management think what a great guy I am, it also gives me the practise required to achieve a 5 for my single engine work in the next OPC.
Of course, this would only be with the F/O's consent and never during LVP's or crosswinds of more than 25kts. That would just be silly.
Harry