Schedule does not have persistence. When the python process stops you lose all jobs.
For a Django app, I use JSON serialisation of input data to store jobs in an sqlite database. the function to run is stored as a python path; a string, that is evaluated when the job is ran. result or exceptions are written to database. That way I can get away with the standard library's schedule just fine. Of course, for these specific jobs it's ok if they run more than once so there's no mutexes needed.