Not exactly... If you use a wide lens, such as 14mm or 17mm, even at f/2.8 you will have a great amount of DOF. It just depends on a few factors. I did plenty of landscape type stuff with my Samyang at f/2.8 that looked great. Sure, stop it down to f/4 or f/5.6 and it got sharper, but it depends on what your after.
Correct, not all the time, which is why I chose to use the word "typically". I did elaborate a bit more in post 8 on the other factors involved (which goes way beyond just focal length).
I originally thought that going into to much detail about the other factors would further confuse things for the op which is while I chose to keep things simple and just focus on correcting the misinformation in your post.
Specifically, your suggestion to "Use the largest aperture (smallest f-number) you can with your lens... Need all the light you can get in poor conditions".