Mostly the money that I wash is metal money.
I have done that as well.
I am pretty good about checking my pockets but sometimes I miss something. This time is was $16 I remembered about after I found a Kleenex had been laundered. Since I know they were not in the same pocket I apparently missed more than I realized. Kleenex is tricky though, it feels like the fabric of the pants.
I often have a little money in my pants, just in case my walk takes me past Savona's, the coffee shop I often walk to. Once the owner let me owe her for my purchase.
I made myself get into the habit of checking my pockets. I regularly use a couple of USB flash drives and a couple of times I almost washed them! THAT scared me into getting into the habit of checking every time.
I rarely miss more than Kleenex, as I said due to the fact I can't always feel it.
For me not to check an entire pocket is shocking. It is possible I only missed half a pocket. These are my tactical quick dry pants I purchased for Africa. I love them for comfort, ease of carrying my phone in a separate front pocket, and all the other pockets I can carry stuff in.
They have:
Two back pockets
Two traditional front pockets
Two little front pockets which are just the right size for my small iPhone
Two big pockets in the front. These pockets have a divider which halves the pockets.