One of the great things about PHP, and other programming languages for that matter, is that it comes with built-in functions. While you can always hard code your way through any problem, using built-in functions will shorten your code and cut the time and effort you need to finish any project significantly. This will give you more time on your hands to engage in other productive activities like checking your FOREX investments or going on a date with your partner.
One easy example where in built-in functions will help you shorten your work is the use of array chunk functions. While you may always convert a string into an array by iterating on string characters, you don’t have to do that at all since there are PHP functions designed to specifically do that for you.
So use built-in functions if you want to be a more efficient programmer.