Occasionally I like to take breaks from doing full pieces to just sketching and relearning basics just to refresh my memory. I also find it very helpful just drawing the basic skeletal frame of a person as a warm up prior to “serious drawing”, often its just as important to your practice to do this as it is to produce “nice” finished work.
Something I really need to work on is perspective though, amongst everything else. You can never know too much. You should always be sketching or improving your skills. And never be too proud to admit you’ve got a lot more to learn about drawing.