It seems you may be associating quantity with quality.
In the case with mantras, it doesn’t matter how many times you hear it/say it/think it if there’s no intention or actual awareness behind it. You have to follow up actually consider the possibility that you are dreaming. How did you get to where you are? Can you recall that?
What’s happening around you? Is it logical?
As far as your journal goes, quantity may be a valid metric for quality, as a longer journal entry is often reflective of better recall, but, don’t discredit the value of a short journal entry. Something is better than nothing and consistency will carry you a long way to building more recall and awareness.
If your issue with your journal is recall, keep in mind the advice that has already been offered.
Good advice here. Don’t move when you wake up. Leave your eyes closed. Try to remember that dream, that feeling, even if it’s just a little bit. If you find a thread, pull on it, what was before that? Do I remember any images? feelings? sounds?
When I keep a consistent journal, even I’m starting with some days of no recall or just fragments, my recall comes back quite naturally as I keep the journal, so I might not have the best advice/perspective on this.
When I won’t have time to write anything down I often say some part of the dream aloud, helps me remember it later.
If your issue is actually finding the energy to write the journal, you might consider exploring your motivation.