I continue to have issues with her method, but I am giving her t-shirt folding technique a try. Leaving aside the matter of "sparking joy", one issue I have is the sheer amount of effort that would be involved in pulling ALL my clothes out and sorting them in one go. I feel anyone who has problems with low energy will not be able to do everything in one session. It's physically tiring and I certainly had decision fatigue just after dealing with the t-shirts. (As the only place I had to put the clothes was the bed, it had to be completed in one session if we were going to sleep in it tonight!)
So I'm combining Kondo with kaizen[*] and doing the sorting in smaller stages by category of clothing. I also didn't thank any of the items and didn't ask myself if they sparked joy. Instead I stared hard at each t-shirt and asked myself "Does this still fit?" If the answer was "yes", I then asked, "And will I wear it again? Honestly?"
Having pulled all the t-shirts out of the wardrobe, where they were hanging sometimes 3 t-shirts per hanger, I now have one bag of "decent but now too small" t-shirts to take to the charity shop and two bags of "too small but too scruffy to donate" and "they fit but they're too scruffy even for around the house" t-shirts to take to the recycling centre.
Instead of hanging, the t-shirts are now folded a la Marie Kondo in two Really Useful Boxes [TM] on top of the wardrobe. Now to see whether the folding method survives contact with the enemy, i.e. can I keep it up during the normal wearing and washing cycle.
[*] Steady, incremental improvement involving slow steps rather than drastic change.