In my heavy BS playing days, I routinely flat bet $25.
I can't even tell you the amount of times I lost $1,000 or so, sometimes in even an hour or two.
I also recall many times whe re I told myself going in, "Ok, just walk after you're up a hundred or two", and NEVER getting up that much after hours of playing.
Granted, there were many times where I made some decent money (just flat betting) but sadly, these sessions were the minority.