Thats the part I think is different for a professor and a manager. A professor shouldn’t care if you overdeliver. They are not managing a timeline or budget. They don’t know/care if that rendering took you 1 hour or 10. They just care that you have the rendering. I can’t imagine an art history professor asking you how many hours you spent writing your paper, an editor might care but not your professor. So why should your studio professor care how many hours each rendering took? (They shouldn’t because 19 year old Sain never took art classes in high school so it takes him 2 hours to draw a box in perspective. While Art prodigy super star student can speed paint a car concept in 30 minutes. In the end they both need to present whats required. )
Even in the real world people hardly ever ask for “10 concepts”. They ask for you to spend 40 hours to finish Round 1, that has 10 high fidelity photoshop concepts and all the required formatting, mood boards, etc. Designers are going to draw way more than just the 10 concepts, throw out bad ones, remix a few, and eventually narrow it down for the preso. But all within the allotted time/budget.
Over delivering to a client is a bad thing it sets prescient for work moving forward. This week you spent 80 hours on 40 hours of paid work. Next time you deliver 40 hours of work they’re going to expect work at the 80 level. (Unless your in an SF consultancy then its always expected 
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But in college you get the assignment “Show up next class with 10 concepts” One student can show up with the first 10 concepts they did that took them a few hours. The other can show up with 10 concepts, that took them the same hours to do, but then they spent the next 5 hours drawing 10 more concepts, refining them, redrawing and getting the perspective perfect. You’ll present your 10 super concepts and have the rest in your sketch stack on your desk.
What I’m saying: In college the professor doesn’t care if you “over deliver” by spending all the time between classes working on the project (your classmates might). Be the person that spends the extra hours refining your concepts, it’ll pay dividends when you graduate.