Help me understand proofing.

Help me understand proofing.

OK, so, this has been on my mind for awhile now, but I simply do not understand the process of bulk fermentation. I’ve been making the Norwich Sourdough for quite awhile now, and have followed the instructions blindly to what has been written down. However I would like to know why during the bulk fermentation process the folds are at 50 and 100 minutes. What sort of texture and consistency should I be looking for? I understand that bread will proof faster, or slower, depending on the temperature of the room and would like to learn how to adjust my bulk rising time for that.

I apologize if this seems like a silly question, but my rather excited sourdough filled brain really, really wants to understand the science of these things. As a side note, I have been Googling this question for the past few days and am not sure if I am looking at the answers that are correct or not. Some resources would be wonderful as well. Thank you in advance for everyone’s help.

Source: Fresh Loaf