IANAP, but when I used to write code on my Atari or Amiga, I would right a program, called, eg, "Fred".
I'd spend perhaps hours on it, and add many more lines of code.
The next day, I'd edit Fred, add more code, and then run it.
If I found a bug, I'd correct it.
Then save Fred over itself, so Fred was always up to date. Backup to floppy.
So what's all this malarkey about compiling, checking out, checking in, etc ?