Approval superusers can approve/reject the required approval instead of every user.
You can enable one/more user/s as Approval super user via the Approval Global Configuration screen.
Click the user picker icon, select one/more users and just confirm by clicking the Select button.
An approval superuser can approve/reject via the Approval actions on the issue screen, via the Bulk Approval screen and via comment (it requires that Notify approvals via comment (NAC) is enabled).