Are there any tests to determine starter's ability to make sourdough rise?
I have been struggling for the last couple of months trying to figure out what is going wrong with my sourdough loaves. I have tried Hamelman and KAF's Vermont Sourdough twice, Tartine's Country Loaf about 4 or 5 times and Forkish's Overnight Country 2 or 3 times. Each one is coming out flat, dense, and inedible. I am struggling with determining whether the problem is my starter or my technique somewhere else in the process.
Here is the source of my internal debate: My starter seems to double predictably, every day, after about 8 hours. While I cannot find a direct answer to the question: "Is a starter that doubles sufficient to make a sourdough loaf rise to proper volume?" my gut says, based on related topics, that this means the starter is strong enough. Assuming that's correct, I then question my technique.
What confuses me is that I have successfully made dozens of yeasted boules from FWSY and Hamelman (as well as a few other randoms). So that then makes me think that, at least my shaping, dough strength, and dough handling is good enough to get good oven spring--which leads me back to wondering if my starter is the problem.
I clearly need to do a lot of trial and error to figure out what is going on. My current hypothesis is that I just don't know how to tell when a pure levain sourdough is over/under/properly proofed. But since that will require a lot experimentation, I wanted to try and figure out how to evaluate the starter first. The reason for that is that my starter was made with bleached bread flour--back when I didn't realize that could be a problem--so I worry that he was doomed from birth. I've just grown attached to him so I don't want to give up on him if it's not his fault.
Do you have any ideas of how to test the effectiveness of my starter? Is there a simple sandwich bread that bakes in a loaf pan with all natural starter that I can make to see if it will rise without worrying about shaping technique and spreading?
Thanks in advance for any help or guidance.