One key issue with new design engineers is the lack of practical exposure to the mechanical systems they are designing.
Practical exposure is the hands-on work and feel of the mechanical systems bring designed.
After all mechanical engineering is a very physical field and the way things work in reality is very different than in any imagination of a individual or theory.
It is important to understand “how things work” “how things fit” “how things are assembled”
Most of the time machines have moving parts. It is very difficult to visualize such motion without having seen it and observed it.
Also, the concept of space, proportion and design requires the human mind to learn by looking at the subject.
Most fields under mechanical engineering are very dependent on practical understanding of systems. Example being manufacturing process which require good amount of trials to optimize and understand their mechanics.
In sheet metal stamping, there are so many unknowns that the tooling engineer cannot exactly simulate what would be the result of the process unless trials are taken.