Hi, I'm making a planning for a project, with about 60 tasks (rows) and 20
weeks.

For each task I list who's responsible, by initial. Each cell (60 times 20)
contains the number of hours the person will spend on that task in that week.
Most tasks are running parallel (i.e. one person does many tasks in any
given week).

On a second sheet I wish to add them all up to show the workload per person
per week (for all the tasks).

I would like to use a conditional formula based on the initials, as follows
IF(Initial=true, hours, 0) and add them up per week for all tasks.
Unfortunately, this sum contains too many arguments (60 tasks and more may be
added) or is too long.

The (working) alternative is that I manually select all cells that apply to
person X and add them up with a simple sum, but this is not very adaptable.

Is there a better way of doing this (possibly matrix based)? Thanks very
much in advance.