The Log Hours feature of the CiviVolunteer extension lists the lists all the available and scheduled volunteers within a volunteer project. We have scheduled the volunteers out several weeks and would like to record the hours for the completed days (past days). However, it is requiring us to enter a value greater than zero for all volunteers listed, even those who are schedule in the future. The Actual Duration field is required. Do we need to wait until all the volunteer roles are completed before we enter the actual hours?
You're not doing anything wrong -- that's just the way the form was designed.
I think it's time this form got an overhaul. Conditional validation would be helpful in this case as well as some others. As an example, I seem to recall someone else pointed out that if you mark a volunteer as a no-show, you still have to enter a non-zero value for the actual duration. Clearly, that's nonsensical.
Full disclosure: CiviVolunteer is primarily maintained by a small development shop of which I am a part. Unfortunately we are not in a position to do unfunded work, but we'd be happy to improve this feature with funding or to help whatever developers you might have at your disposal, provided they contribute the improvements back to the project.