Just discovered the hard way that github screws users who use workflows to build on macOs or windows os.
You get 2000 minutes per month free build time on private repo.
Linux = 1 x 1 minutes
windows = 2 x 1 minutes
macos = 10 x 1 minutes
161 minutes of testing mac os = 1610 minutes off the month!
138 minutes of testing windows = 276 minutes off the month!
If you are not testing workflows you probably wont hit the limit, unless using macOs.