And, of course, there's always the weather to consider. If you live in a climate where the weather forecast calls for a foot of snow all the time, you do have to find an indoor venue so you can work without freezing your tush off!
When I lived in New York City, well, we didn't get that foot of snow all the time, but it did get very cold, so I would find an indoor venue such as my high-school gym, and I would get a catcher, and I would work on this and that. There was always a two- or three-week stretch we used to refer to as "Indian Summer, Part 2", mid-January, where the daytime temps would hit the mid-70s and I could go outside---we would find an unused playing field and I would work off the mound, sharpening up my control or working on a newly-acquired breaking pitch.
My pitching coach used to say "Throw every day", and so I did, sometimes just five or ten minutes, other times the equivalent of a full nine-inning game, with the result that I never got a sore arm! 8)