Whether it's general knowledge or the fundamentals of some important skill, we often scold ourselves believing "I should know this already!" There is nothing to be ashamed of in going back to the fundamentals of an important skill; it is a necessary part of the pursuit of excellence and a sign that your pride is not getting in the way of your growth. It can definitely hurt my pride when I stumble across my blindspots and limitations, but I try not to let self-judgement, shame and impatience get in the way of me learning.
This pragmatic humility is one of the many areas of my life where I practice and practice but never reach perfection. Of course, finding a balance between sufficient confidence to act and enough humility to keep learning is one of the tricky things in life that only saints could be expected to master. So we self-aware, growth-oriented humans keep practicing, hopefully laughing at such thoughts as "I should already know how not to shame myself for not knowing this already!"
Part of the impatience in "I should know this already" comes from confusing basics and fundamentals. A basic skill is easy, at least once you've learned it. Practice of the basics is for novices and boring once you've advanced. Even though many years ago it was important for me to learn the basic reading skill of sounding out words, I doubt it would help my literacy now to practice each individual sound of the words in a picture book. If I were forced to do so, I would get impatient.
Fundamental skills, on the other hand, can only be maintained through life-long practice. Even though fundamental skills are necessary for the development of advanced skills, the fundamentals can never be perfected. You need to be able to run, at least at a basic level, before you can play soccer. But even after you're a good soccer player, you could still improve your game by becoming a better runner. Humility is not an characteristic we either have or do not (like blue eyes), but an emotional/cognitive/social skill that can be developed. We can mature and develop as humans in much the same way as we can get physically fit. As we develop our fundamental social skills, we can develop more satisfying relationships.
Great athletes and artists practice the fundamentals of their craft for the entire duration of their careers. Self-aware, growth-oriented people continue to practice the fundamentals of being a good person, whatever that means to them.
As a Rolfer™ I work with the fundamentals of movement, such as walking, standing, sitting, relaxing, breathing, and balancing. Although I have been studying efficient movement since I was a small child, I continue to learn the fundamentals. I am happy to say that I will be learning to walk until I die.