Many, many years ago, and many thousands of miles away, I was a young man in the military. One summer, our commander had us form up a mountaineering school with primary focus on rappelling. As one of the instructors, my first class was how to tie knots, not not how to tie knots. However, I only needed to teach those knots that were applicable to a vertical rope experience.
So, I taught basics: square knot, granny knot, half-hitch, bowline, and a prussik. I suppose that a prussik may or may not be an adjustable knot, depending on how you look at it.
To this day, I believe that those knots are the only ones that I can tie without thinking. I have to think to tie a tautline and some others. If I am just setting up camp on a nice day, it doesn't matter. If I am out in the middle of a blizzard at 12,000 feet with the sun setting, then I may not have much brain power left, so I have to keep to just the knots that I can tie automatically.
I wonder if many of the thousands of my knot students can still tie anything after all of these many years. I guess knot.