SIP Bakes getting better

My process is nothing special (I think). In short:

• From my 100% hydration starter in the fridge, take a portion and feed with 60% hydration. I do this around 10PM on day 0.
• Repeat 2 more times, 12 hours apart on day 1.
• Morning of day 2
  • mix flours and water, autolyse for 1-2 hours, use all WW flour and as much bread flour as to make this mix 100% hydration
  • add built-up starter, remaining flour, mix briefly
  • add salt, mix until desired strength (I use an Electrolux for this. I think it is a different brand now)
  • coil folds about 45 minutes apart for the next few hours, about 5 times but until you have the strength you want. My dough is close to 75% hydration
    • Due to sticky dough I mist the wood bench with water and use wet hands
  • finish bulk ferment around 10-11PM (temp dependent)
• Evening Day 2
  • Divide into two (I make 3.4 lb dough for two loaves) onto lightly floured bench
  • Do not pre-shape, but pop any large bubbles on surface
  • Gently, but tightly shape for bannetons
  • Cover bannetons with rice flour
  • Place dough in bannetons, seam side up (I do not use liners)
  • Cover and leave for about 1 hr at room temp
  • Transfer to fridge for overnight retard (my fridge hovers between 38F- and 42F), about 10 hours
• Morning Day 3
  • Fire up over to pre-heat (500F), take bannetons out of the fridge to warm slightly
    • Oven has baking stone (horizontally centered) and cast iron pan below (for making some steam) all the way to left so steam can easily get around the baking stone
  • 1-2 hours later invert bannetons onto parchment (very gently), place two loaves side by side on peel
  • Slash loaves with shallow (about 25 degree) undercutting slash about 2/3 to one side of loaf
  • Now: my over is not great at retaining steam so
    • Spray/mist top of loaves just before loading into oven
    • Load onto baking stone
    • Cover oven window with towel (to prevent water spill and cracked glass)
    • Empty hot water in cast iron pan
    • Remove towel, Close
  • After about 5 minutes, open, spray/mist top of loaves, quickly close, reduce to 480F
  • After another 5, repeat
  • After 20 min total, open and vent, make sure cast iron is empty, rotate loaves, reduce to 450F
  • Bake approx another 20 minutes until internal is just up against 200F
  • Oven off, door ajar, let cool this way for about 1 hr. It helps the crust in my opinion

Now, I suspect that the blisters are more the result of the overnight retard, but the over spring, ears and opening up comes from tight dough, good slash, and an appropriate amount of moisture. There are many different ways of doing the moisture, but this method works best for my situation.

Hope this helps.