Understanding the plan before changing my insulin

I've been trying to understand what happens when someone switches insulin or starts a new insulin routine.

I know doctors consider things like current insulin use, glucose patterns and individual needs, but I'm curious about how the starting dose is decided and how the response is monitored afterward.

For people who have gone through an insulin switch, what was the process like? Were there frequent follow-ups at first? What information did your doctor use to decide whether the new plan was working?

I'm interested in the decision-making process behind these changes rather than just the final prescription.