If you skip the laborious process of correcting it everywhere, and just make a note, you have to remember to read the note when you type it up.
Inserting scenes can be a bear, too. Yes, you can write out the scene on other sheets of paper and interleaf them, with arrows and notes this is where that scene goes. . . .
Once you find the location.
It's a lot harder to track things down in the manuscripts. What that character was, what your hero said, why the villain chose that -- and where to stick the scene.