To continue with the above thought, it’s tempting to let students slide, especially when they’re bright and the faculty member is overloaded. "I know I said I’d have a hypothesis for you today, but I’ve been real busy. I mean, I’ll get my thesis done before I graduate." mentors should be reasonable but also be demanding. Insist on regular appointments. Insist that the student do the work that was agreed upon. And insist that the work be high quality. Do not settle for sloppy, incomplete, or badly-written work - even if the student gives the strongest assurance that it will all be better in the end. Generally, what you see now is what you get later.
At the same time, mentors should remember that these are not graduate students and this is not a Master’s thesis. What faculty should expect is undergraduate work of the highest quality, and our students rely on us for help, prodding, and on-the-job training to achieve that.