Quick Question! - About the original intended design of Premiere Pro

Oh, you are doing long form. 

I do hope you are working in Productions mode, not the old stand-alone single project model. The original process simply isn't capable of handling the size and scope of long-form work in the ways that the Productions mode does.

Read through those Productions documents. Please, for your sanity!  😉

anytime you want to make a minor edit, you woul need to go back to the sequence-scene, make the edit and then copy and paste it back to the master sequence

By @Touri

If you make a change inside a sequence which has been nested into another sequence, the change will occur in the other sequence into which it was nested.

It was designed to work basically any way you want to work. Why? Because of the currently several million daily users, the most amazing thing is that no two users work alike.

Noted expert in pro workflows @Jarle Leirpoll has a huge book, over 1,000 pages, on nearly every aspect of professional workflows at speed in Premiere. It's a bit dated in some respects but is still the best overall guide. I bought the ebook, and found it so awesome, massively detailed, that on seeing a paper 'real' book on a shelf, I simply grabbed it not caring about price. It's that useful.

Jarle’s Book “The Cool Stuff in Premiere Pro”

Springer Site for Jarle’s book paper & ebook The Cool Stuff in Premiere Pro

Jarle notes that he typically works in broken up sections, then has a master sequence where each section is a separate nest. Others do different things.

There's very good advice for working from 'standard' through episodic and long form and everything else in the following documents ... well worth the time to read. The best docs Adobe has put out really ... and the "long form" doc has simply most of the best advice for many standard editing processes, no matter whether you will ever do any long-form.

Premiere Pro Productions Introduction

Using Productions in Premiere Pro

Adobe Long-form and Episodic Best Practices Guide 

Jarle’s blog expansion of the pdf Multicam section: Premiere Pro Multicam

Why couldn't you just make your edit and save your new project with a different file name leaving the original in tact?