It chaps my seat when I'm moving files and it "starts over" in the middle of a job. It only takes a moment to resolve it but it's another thing to "check for" when you're taking pics in a very specific order.
I was doing a series of towers last week and they had to be kept in order so that the client can review them and know which is which for "repairs" etc. Right in the middle of the project the "Numbering Scheme Bug" bit me and started back at 0001. When I realized this (back at home in the office) I had to step back, sort them by date taken and then rename them to keep them in order. Had I not noticed and simply "Bulk Renamed" them in numeric order the entire project would have been useless to the client. I'm sure I could have figured it out after the fact by the date/time of the original files it would just have caused me some embarrassment, extra work, and DELAYS to the client.
Like I said it only takes a moment but I'd like to have more than 999 available. Truth be known even if the scheme was 9999 I'd still be here complaining LOL.