How hard is it too cross-train jobs in the Air Force??

For those in the air force, did you cross-train? How many job opportunities are available for cross-training? I know this is usually only offered for undermanned jobs. Or is it better to stick with one specialty?

cross training in the air force?

I’m still looking for advice about cross training into space exploration in the air force. anyone with some knowledge of this career field, please give me a heads up.