What I’m doing for a sponge stage isn’t actually either of those. I’m not making a sourdough, and it doesn’t sit overnight. If it sat overnight it would eat the house – well, probably not if you kept it cold enough.
Warm water (or milk; I start with four cups of liquid which will wind up making three loaves), sweetener (honey or sugar or maple syrup, but something with actual sugars in it to help feed the yeast), yeast, and about half the flour; if some of the flour will be low or no gluten types, the half going in the sponge should I think be the higher gluten flour. Do not, repeat do not, add any oil or salt at this stage. (It’ll probably work without the sweetener, if the yeast is good and fresh; only the flour, water, and yeast are really essential.)
Texture should be about like thick pea soup. Beat well with a large wooden spoon or similar, but if there’s a tiny lump or two left it doesn’t really matter.
Let rise in warm place until doubled in size. Cover to keep drafts out, but not with a towel unless you use a bowl a lot more than twice the depth of the original mix! if you misjudge the timing at all you’ll never get the sponge back out of that towel. Cover with something easy to wash, like a plate.
Depending on temperature it may take about 35 minutes to an hour to rise. Set a timer. If you forget about it, it’ll climb out of the bowl and make a huge mess all over the place.
When you come back to it you’ll see why it’s called a sponge. Stir it down; add oil and salt if/as desired, and enough flour so you can start kneading it. Put more flour on your kneading surface, and knead well, maybe 10 to 15 minutes, adding more flour as needed every time it starts to get sticky.
Put some oil in the bowl, roll the dough around in it till it’s well coated (this and the oil in the pans is usually the only oil I put in the bread), cover, let rise until doubled again.
Punch it down, pretty much literally: shove your fist into it with some vigor about 30 times. Let rise till about doubled again.
Take it out of the bowl and form it into loaves. Put enough oil in the bread pans to coat well and put the loaves in first upside down then turn over so they get coated with oil. Cover with a towel, and let rise the fourth time; it should wind up well over the top of the pans. Then bake.
(I never put salt in it. The multiple risings, combined with quality whole wheat bread flour, maybe some unbleached white, and a cup or two of some other flour such as corn or rye, give it plenty of flavor – not just for me, whenever I make it for other people it disappears in a hurry.)