As others have said it really depends. Shooting mid day at 1/80 one could expect a proper exposure at f:12 which isnt very long at all. If you wanted to shoot at f:12 but increase exposure time to create motion blur, such as if you were shooting a waterfall, you'd need to cut back the light. You can't dim the sun (i've tried) so you'll need an ND filter. An ND5 would do, reducing your time from 1/80 to 1/5. The rocks will be nice and sharp, but the water will be gauzy, just the way you like it. ND filters are really necessary for a lot of work, and are often overlooked because it's one of those things you don't think about using unless you have one.
I currently don't even own any myself, but I should.
Shooting at night the sun is already "dimmed" so you won't need that ND filter, just increase your exposure time to whatever light is available.
i love new cameras, no more f:8 and one half-ish