• Does paper stock determine the angle paper at which paper should be cut?
  
• Is there a general guideline for how often trimmer knives should be sharpened or replaced?
  
• What are some tips for optimizing the use of corner rounders?

Does paper stock determine the angle paper at which paper should be cut?

Yes, the following should be considered general rules of thumb:
Soft Paper: 19-20 degree angle with low clamp pressure
Regular Paper: 23-24 degree angle with medium clamp pressure
Hard Paper: 30-degree angle with higher clamp pressure
For more information, read Trimmer Knife Lifespan for Guillotine Paper Cutters article. 

Is there a general guideline for how often trimmer knives should be sharpened or replaced?

Yes. The following should be considered general rules of thumb:

Standard Steel Knife Blade: Replace after 8 hours of operation
High-Speed Steel Inlaid: Replace after 16 hours of operation
Carbide Knife: Replace after about 160 hours of operation

What are some tips for optimizing the use of corner rounders?

Using the correct thickness for the corner rounder's die, emptying the waste tray, only cutting the correct material, and keeping the blades sharp and new are all critical for optimal functionality. Read more about corner rounder tips here.