Oh... I have so many regrets. Just like many others here I would always design outfits while thinking "Yes, it's a bit detailed but it's totally worth it!", only to realize a few chapters later that NO, it really WASN'T worth it!
One of the latest dumb things I did is the furry part on William's Coat, especially because I needed to shade it AND his bag was overlaying parts of it. That made it far more complicated than I expected. Never again.