Theres nothing wrong with the cut and paste method, doing that means that you take on some of the styles of the original programmer.
I wrote all my own code from the start, which might not have been a good thing, every time I look at someone elses code it does my head in, I can only really follow my own.
When you start first off, the code probably isnt gonna be your major difficulty, I found that initialising the chip and other setup and assembler issues were the problem, not a lack of code skills, learning the 'system' for me anyway was the hardest part.
Speaking of style, every programmer has is own, if you have experience of ladder logic, then some of that will show in your code.