It is ok to use mixes from a box. I use a box mix sometimes to make cake pops! But, just don't use a box mix all the time!
With a box mix it is good to train or practice! Like lets say you have trouble putting things in the oven. Every once in awhile you can use a box mix!
Pudding and Jello are one of peoples favorites! I say that, pudding and Jello are NOT the same as cake mixes from a box! I use those all the time! So, pudding and Jello is a thing every cook uses!