> These should probably be filed better on day one
Maybe, maybe not! I've optimized aggressively for writes (common) over reads (rare) - I don't want to even waste time deciding if I can throw something away or not, so I also keep everything that isn't super obviously recyclable immediately (mass mail, autopaid bills for less 'important' things like internet/utilities, most receipts since I don't itemize my deductions, etc.)
Anything sent to me goes into either a yearly "keep long term" (10+ years - tax docs, house/car stuff, etc.) or yearly "keep short term" (2+ years - insurance receipts etc.) folder in a filing cabinet where it can be forgotten about. Even that's over-complicated IMO - I haven't gotten rid of any folders from either category. If I need my hard copy of something, I probably need it for a specific year anyways. Sorting into more categories doesn't help much - I'd still have to remember which category my 401k documents went in (tax documents? did I have a financial folder? was my system still the same in 2012?)
Hand written notes are slightly more complicated - I actually read my notes enough to optimize reads a little by scanning them in to save me the hassle of opening up my filing cabinet. Still extremely streamlined - I symlinked the default location to a single dumping folder where I actually want them (I:\home\scans\) without needing to select anything. I keep the default sequential numbering naming scheme. I got a sheet fed scanner so I don't have to keep lifting the lid of a bed scanner. I setup a shortcut on the scanner so I press the scanner touchscreen twice ("Shortcuts", "Scan to File"), and a file appears. I don't bother with OCR - my handwriting is terrible, a computer probably can't read it, I probably can't read it.