I am a stickler for this! Make your bed everyday. I think it's so nice to walk into our bedroom and see our bed nicely made. And it's so much nicer to hop into bed when the sheets are crisp and cold and the covers are neatly arranged. I just cleaned our duvet cover and am about to stuff two down comforters into the duvet for the winter. It makes the bed so cozy! Try it.
And if it's time for you to get new sheets or bedding do it! You deserve it!
P.S. Making our bed is VERY simply. I don't use the flat sheet, it drives me nuts. All we have is the fitted sheet, a duvet and pillows. So making our bed is quick!