Hello all, I have thisevening baked my first sourdough loaves. This was my
procedu

Sunday mixed 100g water with 100g white flour, left out, covered
Monday bubbles appearing
Tue added same again to increase the volume so I have 400g sponge, left
out.
Wed kneaded sponge flour, water and salt together to make full dough, left
out some hours then refridgerated.
Thurs turned out dough, divided, shaped with minimum action to retain gas,
rested 1.5 hrs and baked
Not a bad result but I have some questions.

I mixed up a small ferment from flour and water and baked four days later.
If I keep a starter alive in the fridge I can see it will save me a couple
of days but there must be some other advantage. Why not just start a new
starter every time?

What is the best proportion of flour to water for a starter? I did 50-50 by
weight or 100% hydration but I see a drier starter is sometimes recommended.

I calculated 65% hydration for the final dough then added another 200g of
flour (To make 1200g flour to 65g water or 54% hydration finally) because it
seemed so wet. The dough was still suprisingly liquid. Is that really the
right degree of hydration?

I remember from when I used to brew beer that aeration was considered
essential to get the yeast count to increase. I haven't seen any
instructions for sourdough which say to get air into the starter or the
sponge to get the yeast increasing. Is this not done?

Thanks,

Ti9m W