I just came upon all of your very detailed and very helpful instructions for croissant. I have made them when I lived in Britain with great great success. The layers, the flavor. The butter/flours are different in Britain compared to my home (Canada).
I have been trying without success to re-created those fabulous flaky and oh so tender interior croissants.
I have tried strong (hard) flour, all purpose, combination strong and pastry flour. I've tried a local mill's strong (bread) flour but it seemed too weak. So far the all purpose produces the best in terms of structure.
I am careful to chill everything. I proof correctly but the end result is a heavier croissant that tastes wonderful but is more of a roll with layers but not distinct enough to be called a true croissant if that makes sense. The next day they are too dense.
I've done doughs that are prepared the day before and refrigerated over night as well as same day dough which incorporated a small amount of butter in the initial mix with the majority of butter rolled in after chilling the dough.
Anyways, the long and short is I would love to try your recipe using a poolish (pre-ferment). I am familiar with a poolish as I make baguettes often. Just not sure the ratio of poolish to the croissant recipe.
Thank you very much for your time.