yup i was editing my comment when you replied

The problem is that you can only do it ONCE with a different counter because it says: "under the condition that the second security is held until settlement of the initial sale."
That means you cannot buy and sell multiple times in a day with cash account, so that sort of rules out day trading with cash account.
I encountered the problem when I was trading Lloyds during Brexit. My solution was to transfer my warchest to IBKR to give me a cash buffer...