Missing hairs when you shave
The most annoying thing that happens to me is missing patches of hair when I shave. I spend the time to shave and clean everything up, take a shower and go out. While I am out I rub my chin and notice a patch of hair that I completely missed. Since I shave so rarely anyway, the hairs tend to be somewhat long and very awkward looking.
I think that the best strategy to avoid this problem is to do a really thorough shave each time, especially if you only shave about once a week like I do. I use an electric razor and go over my face a bunch of times, until I don’t hear the shaver making the noise that it makes when it is cutting hair.
If you do shave every day, you don’t have to worry about this as much since your hairs will be so short anyway that nobody will really notice.