Student projects like the Rocket Team are funny things. You notice quickly that you're simultaneously overqualified and out of your depth, and that these two feelings are actually describing the same thing.
Overqualified, because the theory you spend hours on every day is orders of magnitude more complicated than what you need to build a functional L2 rocket. Out of your depth, because the 90% of the work that actually matters is everything around the theory, and that part, nobody really prepares you for.
I was responsible for the ejection system: the module that fires a charge of black powder at a programmed altitude to deploy the parachute. The physics is straightforward. You size your igniter, calculate the current through it, make sure it's enough to ignite. We did the calculations, they checked out, the circuit was ready.
Then we tested it, and nothing happened. The altimeter sent its signal, the circuit closed, and the igniter just sat there. We spent a while debugging before realising: the 9V battery couldn't deliver enough current in a single burst to heat the nichrome wire to ignition. By voltage it was fine. A voltmeter showed nothing wrong. The model said it should work. It didn't. We switched to a LiPo, and it worked immediately.
No amount of theory would have caught that. We needed the test.
The parachute system had a similar lesson. We used the Pflanz method to estimate opening forces, sized the shock cords, calculated safety factors of 3x. The engineering was careful. Then we did a drop test in Crans-Montana, and the parachute was immediately unstable, the suspension lines were free to slide through the swivel, so it couldn't hold a steady shape.
The fix was zipties.
The shear pins were perhaps the clearest example. The question was: how many nylon pins do you need to hold the nosecone in place during ascent, but allow the black powder charge to separate it cleanly at deployment? In theory, you'd model the explosive pressure, the shear strength of the material, and work out the number analytically. In practice, the document we wrote at the time says simply that this turned out to be "complex and imprecise to estimate theoretically", so we dropped the nosecone from increasing heights until we understood the failure mode, then verified that 0.6g of black powder cleanly broke two pins. Done.
What strikes me in hindsight is that the theory was never the hard part. The physics of an L2 rocket is, genuinely, not that complicated. The hard part was the judgment layer on top: knowing when a model was good enough to trust, knowing when to stop calculating and start dropping things from heights, and then actually trusting what the test told you when it contradicted your prior.
I don't think this means theoretical depth is unimportant, the stakes just weren't high enough here to need it. But for most things you'll actually build, I suspect the bottleneck is rarely whether you solved the right equations. It's whether you tested the thing, and whether you trusted what the test told you.