I am looking for pros and cons, what works best for people...

Let's say I have a pile on my desk that includes 2 weeks worth of unopened mail, some previously opened and unprocessed mail, the contents of my brief case, and all the stuff I shook out of my kids' backpacks after not getting any papers from them for 3 weeks, clippings from newspapers and magazines, receipts from a trip and daily life, and few nuts, bolts, fabric samples, and extra office supplies.

Do I pretend the whole mess is in an IN box and process it that way?

Do I do a presort? Such as trash, bills, reference, putting parts of documents together, like items together, etc., so that I can batch process?

If I have done a presort, should I file one item at a time? Or should i collect a stack to file in reference and just put the stuff pertaining to active projects in their designated area?

Does it matter if the A to Z reference file is huge?

Is there any rule of thumb pertaining to items that fill a single category but will ultimately need further sorting, such as receipts, recipes, photographs, kids' art work?

What is most efficient?