So often it seems as if teachers only recognize that a student is having difficulty and take action when it's too late, when the student has already fallen far behind. What we need to recognize is that the easiest time to address potential problems is when we see that a student is overwhelmed but not yet to a point where they cannot function effectively in the classroom. I wasn't even aware that this academic limbo existed until I found myself stuck in it, and maybe that's because it is usually such a short window (either because the student pulls him/herself out of it or they fall quickly). Regardless, it's something that should be addressed when possible, and there are warning signs in student behavior even if they're still handing work in on time.
Yes, it's imperative that students learn to ask for help, but speaking from experience...that isn't always easy, especially when that means that you have to open up to a person you may or may not completely trust. It's hard for some students to admit that they have too much on their plate and they don't know how to handle what they already have. This is just one more way in which teachers must understand the needs of their students on an individual basis. While some students thrive under pressure, others may crumble. If a teacher can establish rapport with students, it makes it infinitely easier for a student to approach a teacher and ask for help when it is needed.