Programming a new microcontroller often takes a longer time due to the new register handling methods and not knowing what bit does exactly what. The same goes for debugging as well without saying. This is why programmers quite often use breakpoints in their code and step through it using a debugger. But using a debugger might need additional hardware (most times expensive) and also additional time. Being an Arduino fan boy, one thing we all can agree is using serial print statements for debugging and understanding our code makes life a lot easier.