When we think of the mental noting, on the very first night of the retreat, all I mention is every time your mind goes off, note, "thinking, thinking" or "wandering, wandering", and that is fine. And, that actually is fine. You can be very broad in that way, every time that the mind goes off note, "thinking, thinking", and that is fine. That will work in its own way to help to let go of your thoughts, to help not to attach to your thoughts, to help to get back to the meditation subject. It will work.
On another level, though, if we can be more specific, then we not only note the thought and let it go, but we kind of collect information that we will use later. For example, with future thoughts, if we actually know "planning, planning", and throughout one course of the day we are finding out that 70 % of our wondering thoughts are "planning, planning", ok what meditation technique would be good to use to counterbalance that? Death reflection? Yes, because we know death reflection is an opposite type of thought to future thoughts. If we see we have a lot of future thoughts, then it is good to do some practice on death reflection, to help to let go of future thoughts.
Now if we see we have a lot of angry thoughts, all through the day we are having a lot of angry thoughts, then we can say to ourselves, "Oh well, looks like I need do some Compassion/Lovingkindness." So when we are more specific with the mental noting, then it actually pushes us to do specific other techniques that we might not normally think about, in order to make an antidote, in order to resolve those thoughts that are caught up with those angry thoughts, with future thoughts or whatever. So both types of mental noting are ok to follow, they are both ok to do, broad thoughts in the mental noting, broad mental noting, or just specific. The specific can be more helpful in a future practice.
Now, if you can't think of the specific right word straight away, say you are wandering, and all of a sudden you kind of see it is future, you kind of see it is aversion, you kind of see it is this or that, you don't know what to label it, then "thinking, thinking" is fine, or "wandering, wandering." Very, very general when you are not clear. Because when you are not clear, what often happens is, "What kind of thought is this, is this a future or past thought, is it this, is it that?" All of a sudden you are off, and you are actually off into worry and doubt. So if it is not clear straight away, just use a very broad term, but if it is clear, it is very helpful to be very specific.
Now, I'll add more to this: the mental noting that you use is the reality of what is happening to you. This is important.
Imagine we are sitting in the hall. We hear someone talking outside the doors, and we can note, "hearing, hearing". What happens for many people is that they note, "talking, talking". However, the talking is what is happening over there, that is their world, the reality of our world is that we are hearing, hearing.
The minute people note, "talking, talking", what often happens is that they are thinking about who is talking, but if we note "hearing, hearing", that is us, that is what is happening to us.
We realize we are off, we come back to the meditation subject. So you have to be careful with the mental noting, that it is actually what is happening to you. The car beeps a loud horn outside, note "hearing, hearing", don't note, "horn, horn", because that is the other world, we want to note just "hearing, hearing".