Is it possible to show sum of efforts for all tasks for a day in Org-Agenda day title? (So that for a week agenda there are 7 sums for each of the day, in their respective titles.)

How could I achieve this?

If that is very difficult, what would be the closest alternative?

Also, I would like to use a predefined Effort value for all tasks lacking the Effort property.

I would like to show sum of efforts for all tasks for a day in Org-Agenda day title. E.g. for a week agenda there would be 7 sums for each of the day, in their respective titles.

I think this could be done somehow by manipulating the org-agenda-format-date variable.

By default, this variable points to a builtin function org-agenda-format-date-aligned, but I suppose it can be reset to point to a custom function to include the sum of efforts in the date line.

Could you please help me define such a function?

Also, I would like to use a predefined Effort value for all tasks lacking the Effort property.