Changing the code and seeing the results was even on the machines of that time practically immediate with the first versions of the Turbo Pascal, as long as the program and the source were able to fit in the RAM. And the interaction was designed to be immediate too. If I remember correctly the compilation error didn't cause infinite screens of report, it just repositioned me to the line where the error was. If the cause was a typo, I was able to edit recompile and run in a second. Most more recent tools have other ideas, requiring more unnecessary activities from a developer.