Personally having a programme to follow takes all the guess work out of my training. There is nothing worse than going into a gym and trying to decide what to do when you get there. Knowing exactly what I need to do and crack on with it. Without a programme you can risk half – assing it!
You may also find that having a programme helps with consistency. As I have said so many times consistency should be your number one focus. Being consistent without a programme is still better than having programme and not being consistent with it.