I’m no expert, but I’ve made them. I would say that would be the least of your worries w Croissants
I’ve made them once and once was enough.
He’s basically making a preferments like you do when you make sourdough. This is to develop flavor. Maybe it adds to the crispness I’m not really sure about that. But I always use some type of pre-ferment when I’m making sourdough. How much of the flour water mixture depends on the recipe or more precisely, the formula and percentages used for bread formula aka recipe.
But I digress. There’s plenty of good croissant recipes out there. The problem lies in the butter and getting the right temperature between chilled and cold. Using those machines to laminate the dough makes it all look easy, but without those machines, doing it all by hand? I never want to do that again. After all the work I did, because the butter temperature wasn’t quite right: no laminaton in the final baked result. That’s right: no flakey layers. And I actually made these croissants for a bread meet up group, so we all baked and all compared results. I wasn’t the only one that made the exact recipe, but we all had very different results. Mine was a big Bread lump That looked really good on the outside. Another person had spectacular results using the same recipe. It’s all about getting that butter temperature correct and it’s done more by feel and knowledge then somebody telling you to take the temperature of it and it supposed to be X number of degrees.
Hopefully, someone else here can give you better info because my answer is stay away, stay far away, Buy them! LOL.