I think you've shown that you're holding FC through the day so testing once a day is fine. But, please dose 4oz dichlor until the residual FC is at least 3ppm.
As far as running out of powder, you can conserve by using one dipper - if the sample turns pink, it's enough.
I think you're on the right track - just have to keep the FC above minimum at all times.
Are you uncomfortable with FC at 2.5ppm or 3ppm? I don't understand.
How much total dichlor have you used so far?