I run a R-Pi zero, no special setup, just an indoor aerial and record around 1500 aircraft daily.
Live in London, around 15 miles from Heathrow. See quite a bit of commercial traffic overhead usually at around 8000 feet if heading to LHR. Have a municipal airport around 4 miles away but don’t see too much activity from there, probably due to indoor aerial.
Currently on holiday in Oceanside, California, brought Pi with me, quite fascinating to see different traffic. Aircraft count lot less, around 1100. Busy municipal airport close by and see quite a bit of activity but commercial traffic tends to be light and around 20000 feet. Again, only indoor aerial.
Very interesting seeing the totally different activities in the two locations.