Something Charles De Lint said on Saturday was to stop a day's writing at an 'unnatural breaking point'. He suggested stopping in the middle of a sentence or paragraph. I'm not sure that works for me but it bears experimenting with.
I prefer to end at the end of a chapter (ideally) or the end of scene. That gives my mind the freedom to think ahead. I can think about what comes next, how I want to write it, what needs to be said or accomplished. If I stop halfway through a scene, I have a hard time getting back into that headspace.
Every single writer needs to find what works for them. There are a thousand tips and tricks. Not all of them work for every person. The important thing is to experiment. Find what works for you, what you like and discard the rest. Personally, I'm really looking forward to getting back into the 'Throne of Writing' (Tm) and starting the next chapter. The plot is flowing!