Bulk assign flexible effort

Hi,

We use the flexible effort type for the vast majority of our tasks as it allows our users to modify their time according to their availability on any given day.

However, when building plans, it's quite time consuming going into each task and setting both the task effort and the assignee's effort.  Does anyone know if there's a way to bulk set this for a group of tasks?  Copying down the effort once it's been set doesn't work.