I've never repeated treatment before personally. Usually when I see bloody poop, I do the 5 days with 2tsp per gallon, then for 14 days, the 1/2 tsp per gallon.
When I was constantly raising chicks, I did have to battle with coccidia on a more regular basis. I just followed the chart and had...
I should note: not always will infected birds immediately show signs of lethargy or etc, (so they might ultimately appear normal or fine) but sometimes the blood comes pretty quickly. Same goes for the other way around. Sometimes you'll have lethargic birds and not see bloody poop right away.
Yes, corid is pretty safe as far as I know. Just follow the recommended dosage in their main water.
Here is an older screenshot of the recommended dosage that I took from this forum.
If this appeared to be a one time poop, I can't help but lean towards intestinal lining. These are older birds, right?
In the end, it still doesn't hurt to be safe and treat anyways. I hope everything goes well!
Doesn't hurt to treat. Its too uncomfortably dark red in color to think it isn't coccidia but at the same time it does look stringy like intestinal lining. Can you share more pictures of the poop? Is she constantly pooping this?