I don’t have a set of clear goals and objectives. I have a very broad problem area and my job is “make this better.” And I’m salaried so I spend about 40-60 hours per week in this area. I think my employer trusts me quite a bit.

For task based jobs by all means figure out a cost and bill by the item. Some professionals do this. I paid my accountant $600 and didn’t care how long it took her.