For many experienced artists, the "grid system" can be seen as cheating and I suppose it is and wasn't available to us as artists until recent times. Be that as it may, doing faces or difficult things to replicate with whatever tools you are using to make your art, can be so frustrating when you continually get it wrong and especially with faces, the end result can end up looking like a human that you dumped in acid. I've seen some of my students be brought to tears by this frustration and a lot of them simply want to give up because of it. So even if it is "cheating" I think that alternative of the kid giving up on art is far worse than using a bit of technology to help us hone our skills.
The way we have been working on it is to take a photo of their choice, zoom in on a table that the school provides for us, greyscale the pic, then set down the grid. The student then has a piece of paper with 1-inch squares that they can work on each individual part of the features of the face one by one instead of trying to focus on the entire picture at the same time. This makes getting the fine lines and the contours of the face correct so much easier. The idea here isn't that we have the kids always using a grid, but instead to actively or subconsciously get them to simply just know about how an eye or a nose is shaped over time and as time goes by they will need the grid less and less. To me it is like training wheels on a bicycle, the idea is always to not need to extra help at some point.
I have seen this process help a lot of students over the years and when they get older they rarely use it anymore. In one particular situation there was a girl who was 12 that really liked the grid concept for drawing faces but now she is 15 and will stop by the classes every now and then even though she is in high school and "super cool" now, and show me a portrait that she has done free-hand and it just makes me so proud.
If you are struggling with complicated things in art like faces, this can be a very useful tool for you as well. The apps are free on all devices and honestly, they are super easy to use. The only thing you will need to do in order to prepare is to either purchase 1 inch graph paper or instead to draw your own by carefully using a ruler. I like the last way better because you can erase the grid lines afterwards and conceal the fact that you ever used it at all!
In there end there is no "correct" way to do art, but I think that if something is getting in the way of your progress, there is no harm in using a bit of tech to help you cross over that hill.
