It would be useful to be able to define when conditions that apply globally across all jobs, enabling things like skipping all stages with a certain name pattern (like, say, not running deploy stages on the weekend) or inspecting the stage to see if it is trying to use a service that's currently down. This would require some changes in Declarative to allow plugins to add when condition types that can't be specified in the Jenkinsfile, won't show up in validation, and won't be available in the snippet generator, and parsing/execution-side changes to support transparently adding any configured global conditions to all stages while retaining conditions directly defined on stages.