When
Choose a small PLA print when you are learning the printer controls.
Then
Use a model that fits comfortably on the build plate, has a broad base, and can finish in under two hours.
PLA is forgiving, widely available, and easy for beginners to observe while adjusting temperature, bed adhesion, and cooling.
When
Choose a larger functional print when you already trust your first-layer setup.
Then
Split the project into test pieces before starting the full object, especially if fit or strength matters.
Short tests expose sizing and warping problems before they consume a full spool and several hours.
When
Choose an AI-generated model only when the shape is visually simple.
Then
Inspect the mesh for holes, thin walls, floating parts, and unsupported overhangs before slicing.
A model can look finished on screen but still need repair or redesign to become a dependable printable object.