Remember the running clock and the clock history across Emacs sessions.

(Org suffers from NIH, and so saving org-clock-history or org-clock-stored-history does not work with the savehist mode.)

(with-eval-after-load 'org-clock
  (setopt org-clock-persist t))

(with-eval-after-load 'org
  (org-clock-persistence-insinuate))

Automatically remove clocks started by mistake and stopped after a couple of seconds.

(with-eval-after-load 'org-clock
  (setopt org-clock-out-remove-zero-time-clocks t))

Measure duration only in hours and minutes, not days, hours, and minutes.

(Important for invoices.)

(with-eval-after-load 'org
  (setopt org-duration-format 'h:mm))