This is a really interesting observation. I've never heard someone mention a "buffer/holding effect" before, but that makes a lot of sense.

I wonder if it's something like... the average individual spends half of whatever cash they have available every year... but the average business that takes investment lets 6 to 12 months of it sit in accounts. I realize the bank would then loan against the money in those accounts, but is it "turtles all the way down"?

I'll have to refresh my understanding of fractional reserve banking, but I don't think a loan from Bank A being put into Bank B and so on can lead to infinite money supply. If I remember correctly it somehow leads to some multiple of the input money being generated. Here's a Wikipedia article about it:

https://en.wikipedia.org/wiki/Money_multiplier#Reserves_firs...

At some point all the institutions sitting on their money eventually does result in that money being sat on, and not being circulated through the economy.