I agree with this as women can be subtle af, and sometimes if they're attracted to someone, their IOIs are given subconsciously and they don't even recognize it. And you have a lot of dudes that don't see it and need a woman to literally jump on top of them to get the hint.you have to be relaxed and to pay attention to your surroundings
most women are shy so most of the time they will give iois that are not easily perceived by a guy
Still, it has to be said many of us just flat out don't get them. I can recognize when they give them to other dudes. Yes, it's often subtle, but you still notice it.