Produce summary workbook sheet with data from multiple workbooks

I have created a template workbook for individuals who work on different sites. The spreadsheets used by each individual have the same headers. The sheets all sit in the same folder in dropbox.

I am wanting to produce a summary workbook within the dropbox folder that automatically populates when an individual updates their workbook.

I have attached mock example of the individuals worksheet for your information.

The questions that I have are as follows:

1. Is it better within an individuals workbook that they record their activity all on one sheet as opposed to having a spreadsheet per months activity? It seems tidier to have a sheet per month but does this make it more difficult to produce a summary workbook?

2. The individual is required to record a patients individual drugs on separate lines but they need to record a unique identifier, age, *** and month worked. Do they need to record all this for each line of drug or is there an easier way?

3. How should the summary sheet be produced - pivot table or sheet with formulas linked to the individuals workbooks?

Thanks in advance

Sean