What happens when everything goes according to plan is that, well, everything goes according to plan.
Which is great.
At least at first.
But what happens when everything always goes according to plan is that you get addicted to things going according to plan.
And when you always want everything to go according to plan, you'll never really do new things anymore.
Simply because the only way that things will always go according to plan is that you follow the same old plan over and over again.
That you do the same old things over and over again.
That you never really try out new things anymore.
And never really learn new things anymore.
So after all, maybe it's not so bad if things don't go according to plan.
Every once in a while...
[Related: I stopped giving a shit a long time ago]