Honestly the big thing nobody talks about is how much your kitchen's humidity messes with rest time. If the air is super dry, letting batter sit even for a short bit can over dry it and cause those cracks you're seeing. I had the same issue until I got a cheap hygrometer to check the air moisture. Now I only rest my batter if the humidity is above 50%, otherwise I pipe right away. Took me like five batches to figure this out but it was a game changer. So maybe skip the rest step on dry days and see if that helps.
Man, casey_palmer is out here using science and I'm just over here guessing. My last batch looked like a dried-up riverbed. Guess I should stop blaming my oven and start looking at the air.