I have 6 PDF files being the result of splitting multiple presentations in PDFs (which had 6 slides on each page). So essentially, now I have top-left pages of all the presentations in one file, top-right in another, middle-left in a file and so on...

That's basically how every initial presentation looked like:

page 1
 ___________________
|  ______   ______  |
| |slide1| |slide2| |
| |______| |______| |
|  ______   ______  |
| |slide3| |slide4| |
| |______| |______| |
|  ______   ______  |
| |slide5| |slide6| |
| |______| |______| |
|___________________|

page 2
 ___________________
|  ______   ______  |
| |slide7| |slide8| |
| |______| |______| |
.....................

How can I merge them together to maintain the order of the initial presentations? I kind of have to do the following:

for index in range(number_of_pages_in_each_pdf):
   final_pdf.append(pdf1[index])
   final_pdf.append(pdf2[index])
   final_pdf.append(pdf3[index])
   final_pdf.append(pdf4[index])
   final_pdf.append(pdf5[index])
   final_pdf.append(pdf6[index])

There is around a hundred pages in each of those six PDFs, so rearraging by hand is out of question.

I have 6 PDF files being the result of splitting multiple presentations in PDFs (which had 6 slides on each page). So essentially, now I have top-left pages of all the presentations in one file, top-right in another, middle-left in a file and so on...

That's basically how every initial presentation looked like:

page 1
 ___________________
|  ______   ______  |
| |slide1| |slide2| |
| |______| |______| |
|  ______   ______  |
| |slide3| |slide4| |
| |______| |______| |
|  ______   ______  |
| |slide5| |slide6| |
| |______| |______| |
|___________________|

page 2
 ___________________
|  ______   ______  |
| |slide7| |slide8| |
| |______| |______| |
.....................

Q: How can I merge them together to maintain the order of the initial presentations?

I kind of have to do the following:

for index in range(number_of_pages_in_each_pdf):
   final_pdf.append(pdf1[index])
   final_pdf.append(pdf2[index])
   final_pdf.append(pdf3[index])
   final_pdf.append(pdf4[index])
   final_pdf.append(pdf5[index])
   final_pdf.append(pdf6[index])

There is around a hundred pages in each of those six PDFs, so rearraging by hand is out of question.