When our children lack executive function, we may need to train them as well as do a bit of scaffolding in that department. My "aha moment" came when I realized that checklists like the Flylady ones are not really pointless and silly (I am used to storing and processing large amounts of data in my mind that I never need checklists). Checklists impose a very important thing called "Accountability" into our children's lives. I was missing that part of the puzzle for most of my own youth.
So, I now make a checklist for my 6 year old. It has 3 sections in them:
Morning routines, Evening Routines and Bedtime Routines. They are very simple and easy to follow instructions.
My child, just this morning was being rather quiet which made me go and check on him - he was reading a christmas toy catalog and got lost in it. All I had to do was tell him that he was running late and that he was not done with his morning routine and I was going to leave the house at 8:00 AM no matter what to get results.

Here is an example of a Bedtime Routine:
1. Drink water
2. Eat vitamins
3. Brush teeth
4. Lay out uniform for school tomorrow
5. Lay out socks, belt, underwear for tomorrow
6. Put homework folder back in backpack
7. Put textbooks back in backpack
8. Put Free Reading book in backpack
9. Sharpen all pencils
10. Put lunchbox, water bottle in kitchen for washing
11. Shower and change

I make a checklist and list week days by the side and put it in one of those "dry erase pockets". My son has become a regular little checklist follower these days and if he follows all his routines every day for a month, he gets to go on a trip to a museum of his choice.
Checklists have made our life less chaotic in the past year. I use digital checklists for my tasks and chores, so if your children can handle electronic checklists, then let them use their phone/tablet/computer etc for ths purpose. Good luck.