Newby question about crust thickness
I am new to bread making by hand and I haven't yet tried any of the more fancy breads unil I have plain sandwich bread down so that I get consistent results. My problem right now is the thickness and hardness of the crust. I am using Peter Reinhart's recipe on page 266 of The Bread Baker's Apprentice. I am kneading the dough with a stand mixer just unil the dough passes the windowpane test (about 7 or 8 minutes). I let it rise, divie the dough, let it rest, form it into loaves and proof it in loaf pans. The recipe calls for 35 to 45 minutes at 350º. The bread feels done at 35 minutes and has an internal temperature of about 185º which is close to the 190º specified in the recipe, and the crumb is perfect. My assumption is that the thickness of the crust and perhap the hardness is directly related to the amount of time it spends in the oven, but since I'm already at the low end of the window called for in the recipe and the internal temperature is close but still under 190º, I hesitate to take the bread out any sooner.
Is there anything else that affects the thickness/hardness of the crust? Or is it just that bread making is an art, not a science, and so try pulling the loaves from the oven a few minutes earlier?