The frequency of NPBs I experience has increased slightly, to the point where I've decided to shorten my payment time-frame (in the store) from 7 days to 5 to try and minimise the time the stock is "off the shelf". (Find and replace isn't working, so I'm going to have to do each listing manually 😞 ). 

Most of the time it (NPBs) doesn't really bother me as I only spend a couple of minutes actively dealing with it and it doesn't really affect my cash flow all that much, but because every now and then some buyers attempt to draw out the process even longer, it's inspired a lower tolerance and less flexibility all-round, unfortunately. (I had one recently where there was no contact or response to my message after 7 days, day 8 I opened the UPI and several hours later I got a message asking me to be patient... I was being patient, but it took too long!  )