Creole cake question.

Creole Christmas Cake
Hi Lindsey ~ I have made this cake for many years, it's delicious!
However, last year, in a rush as ever, I failed to simmer the fruit in the alcohol and simply left it cold, in the fridge soaking for a week, then I made the cake.
My question is, why is the simmer stage included in Delia's recipe, it didn't make the slightest difference to the finished cake when I failed to simmer the fruit first?!
I am this afternoon about to make it again, what should I do!?
Many thanks, your time is appreciated :)