Projects requirements are often pretty open-ended so each student figures out what they think is “enough” to complete the assignment. Everyone will be different – figuring out the requirements, learning to do the work, amount of effort, time to do the work, interest in the subject, personal guidelines, what you “think” the teacher wants to see…
There is a lot more to doing projects than just doing a bunch of problem sets. Is there an opportunity to ask questions to help find some “boundaries” for the work? How “big” is this project based on points? What is being asked? Are you adding in requirements that aren’t there? What are you supposed to learn by doing this project?
This is making a case for giving students more information as part of project assignments. Teacher-provided rubrics are good. Student-developed rubrics are worth considering. Providing the learning outcomes helps students focus their work to ensure that the work they do is appropriate to the actual desired outcomes in a reasonable timeframe.
I ask students mid-semester how much time they spend doing the assignments. I work with students who spend too much time – yes, this is as big a problem as those who spend too little. Some students do it because they are really interested in the subject. Others have study skills problems and benefit from intervention and a reality check.