Nobody's perfect!
This topic is one of those discussion topics for educational purposes. It'll help others avoid mistakes we might have caught ourselves making in the past or even today. I'll start with one I just recently brought up to Moosh about a mistake I've been making in my most recent quests and I'm trying to lean away from. This wont include all my poor design habits from the past personally because there's too many issues to count.
I feel one of my biggest mistakes/regrets in my more modern work now is my tendency to make dungeons almost too item/diverse. I've often favored letting my dungeons allow Link to use their entire equipment list in almost every dungeon, which leads to dungeon design that requires you to always be constantly switching up your items. This preference made me ignore just how much of an issue this is. I tried to correct this issue in the past by providing a way where you can see what items you'll be selecting almost like a rotation wheel for L and R which does help slightly, but not enough to handle with the issue of how much this quest expects you to always change your items. It didn't occur to me until lately that my very principle was the mistake.
I've realized this after noticing some Mario games handle mechanics by introducing a mechanic, then slowly pushing you into the mechanic by repeated rooms of the similar mechanic. I never really seen a random meshmash of variety like how I approach things and realized my approach to this is terribly flawed. This could have been handled better by having a chain of rooms with similar gimmicks rather than constantly randomizing level gimmicks for variety. This would then require players to switch their items far much less, and thus does not impact the flow of the dungeon.
My design philosophy takes dungeon flow very seriously, however, this one mistake heavily compromises good dungeon flow. It's funny how I prioritize something, but also compromise that very same thing by another design preference.
Fortunately for me, I'm noticing this in mid development and I may be able to look over all my dungeons and try to fix this issue as much as possible by moving some aspects to dungeons around or by simply removing some challenges entirely. There are ways for me to improve this situation for my current quests, but I feel with new quests I can certainly take this into consideration and fix the pacing issues in future dungeons by looking for as many ways as possible to expect players to use items less. Heck, even bunching rooms close together based on the item subscreen position will also help in accessing items better than it's currently handled.
So moral of the story people, take a much better care of understanding exactly how ZC limitations are impacting your quest. Something as simple as a subscreen can ruin the entire pacing of your dungeon if people gotta constantly be looking for the items they want just to get around.