Could destroyers have been held in reserve at Dogger Bank?

Should roughly a third of the destroyers have been kept in reserve?

That was a valid option for pursuit or retreat cover, but Beatty's handling showed little understanding of reserves and made an all-in commitment more likely.

Keeping some destroyers back for a finishing attack made tactical sense. A reserve could also launch an emergency torpedo strike or make smoke to cover a withdrawal if the battle turned badly. Fast destroyers would still be able to run down damaged enemy ships after the main action. Beatty did not handle forces with a clear reserve concept, so an all-in commitment better matches his conduct.