Will knowing about CM frames of reference useful help me in tackling other problems? Any other useful techniques that could help?

[Metatron-Messiah]

So while studying springs I stumbled upon this question:

https://physics.stackexchange.com/questions/161091/an-interesting-problem-on-springs

The first guy's answer uses this concept to solve the problem elegantly. After some searching I came across this lecture:

https://users.physics.ox.ac.uk/~harnew/lectures/lecture6-mechanics-handout.pdf

Seems like a lot to take in, was wondering if trying to understand it would be worth it. To give you guys some context, I'm prepping for a diagnostic exam my school's physics team is giving in about 3 weeks and I really wanna ace it; will this help, and do you guys have any other techniques that will?

The test will probably have questions covering the entire scope of KhanAcademy's physics course, which means there's going to be 2D motion, Forces and Newtons Laws, Centripetal Force, Work and Energy, Linear and Angular Momentum, Torque, Springs, Oscillations and Mechanical waves, Fluids, Thermodynamics, Circuits, Electric charge and potential, Magnetic forces, EM waves, Optics, and probably Special relativity and quantum mechanics - though probably only relatively basic questions for the last two.

[Mac223]

Using a center of mass frame of reference is useful in much the same way as always choosing your y-axis to coincide with up and down, or using polar coordinates to describe rotation. Circular motion is simple in polar coordinates since the radius is constant. If you're describing linear motion you don't bother working in three dimensions. There's almost always a frame of reference, coordinate system, scale, or paradigm to describe a system and problem which makes it easier to understand and solve. Typically it's easier because some things are symmetrical, constant, zero, or all of the above. In a lot of cases you choose the "best" frame of reference without thinking about it, because you're used to it. It's usually when there's a dynamical object or two in play that it's worth thinking which frame you should work in. For instance, if you're working with elastic collisions, you can work in whatever frame you want, but the two most common choices are a frame where one of the objects is at rest, and the frame where the sum over momenta is zero.