Kind of a flip side to the instructor, I had one instructor and stuck with him and him alone. When I got into more advanced flying I had another instructor, a complete opposite of my basic instructor, no fun at all but he got me pretty good into pattern flying.
After I had soloed my basic instructor was asked to teach a young student, fine, we flew every Sunday from 8 to noon. The kid showed up a couple Sundays in a row at noon just as we were leaving. Soccer practice, Church and soft ball practice. He never learned to fly, you have to work within the instructors hours. Few years ago I had the same thing happen with a guy down the street. Every time I could go flying he couldn't.
I had another student with all his own gear. He had the time but he always had something new happening to him, back pain, foot pain just all kinds of pain. He just couldn't find the time when he felt good.
I'm retired and have the time but the student has to make the time too. I'll work around there hours but you can't learn if you can't get to the field.
My basic instructor was really good at it and I use the same methods as he did with me. I have had young students that soloed the second day and older students that took a couple months but they all learned if they put in the time.