Hi Brian,
As of a CAD system, Inventor belongs to a group of tools called "3D feature-based parametric solid modeler." It is meant to make precise model geometry (measurable up to 0.00001mm) as a digital twin to compare with actual build. There is a wide range of application using such tools (almost all manufactured parts are designed using such tools).
Within the group, the tools work very similarly. If you learn one, you can easily transfer the knowledge to another system (with an open heart). It is like once you learn driving a car, you can pretty much drive any 4-wheel vehicles.
Please note that the tools only facilitate your design; they should not drive your design. The key is always about what you are trying to design and what problems you are trying to solve, not necessarily what tool to use.
To be a good mechanical designer, you need to have good grasp of your design constraints, spatial relationship, logical connection, scalability, and extendibility. You may have designed one-off parts. In professional world, many parts are reused and repurposed. You always want to keep in mind how you can easily alter a given design for a different need. It takes some experience and good practice, which does not necessarily have anything to do with the tool. Over my 20+ years at Autodesk, I have seen around a quarter million parts and assemblies. Just by looking at the sketches and the features, I can tell how well the mechanical design was done and how closely the design intent was honored. Certainly, not every part is the same. There is always room for optimization (just like the tool itself).
A well-designed model is like a master art piece. It may look simple but it has depth and intelligence built in. You get inspired by it. Designers like that are highly valuable.
Best wishes and good luck!
Johnson Shiue (johnson.shiue@autodesk.com)
Software Test Engineer