Prefect 1.0: que about CronScheduler: is it possible to modify Parameter defaults for runs that are started via CronScheduler? the use case is that manual runs are assumed to be for testing and we want to skip a certain task by default. But tasks run via scheduler should not skip that task.

All clocks support parameters. So you can set parameter on the cron clock and have a case handle the logic. https://docs-v1.prefect.io/core/concepts/schedules.html#varying-parameter-values