Duplicate Values Per Column With Various Row Ranges For Many Columns

I have a challenge related to a excel sheet we are using for personnel planning.

Vertically we have several projects with action items listed row by row in the following format:

- Project 1 xxxxxx
Project management
Project Engineering
Workshop
Shipping
Etc.
- Project 2 xxxxxx
Project management
Project Engineering
Workshop
Shipping
Etc.

Horisontaly on the columns we have dates, day by day for a year +

For each day we chose from a drop down who is assigned to the action item. The problem is when there are 30-40 + projects and each have 20-30 lines of ation items it is hard to get the overview and avoid double entry. I would use conditional formating to do this, but firstly each project is separated by a line containing different formulas and I would not like the conditional formation to change these cells, and at the same time to put this up manually for each row would take a long time since there are 365 + rows.

how a VBA code could solve this little challenge? IT would also be beneficial to have it do the check upon cell change, that way we would not need to manually run the VBA to check.