No, it isn't feasible to edit apex training and triggers immediately in manufacturing environment.
It needs to be achieved first in developer version or checking out org or in sandbox org. Then, to install it in manufacturing, a user with author apex permission need to install the triggers and lessons the use of deployment tools.
But, visualforce pages can be created and edited in each sandbox and in manufacturing.
Only if the page has to do something specific (extraordinary values), it would have to be advanced via sandbox.