I'm not entirely consistent on writing dates. I try to use YYYY-MM-DD whenever I can but I do accept that it is not what people outside East Asia expect.
 Whenever I have something that will be sorted, say files or photos, I use YYYY-MM-DD.
However, if I'm writing a letter (remember those!), I will as often use MMM DD, YYYY as I will YYYY-MM-DD. I find the former nicer to read. I still need to think about about whether September is month 9 or not.