Need to change Gantt chart to track hours in a day through Monday - Friday

Your question is not clear with respect to this file. It does not have any formulas that track progress, and there is nothing weekly here. The calendar starting in column I is grouped by week, but it does not track weekly progress, it tracks daily progress. You must manually enter percent progress in column D. The shading starting in column I shows progress based on that percentage using conditional formatting, progress to the nearest day. It is not clear where you would want to show hours in a day in increments of 15 mins.

Please provide a copy of your that shows what kind of results you want to get. Just mock up the values, we will help with formulas.