In my opinion, the visualization aspect of MILD is the most effective part of it. It sounds like you haven't been doing this. When you're visualizing what you should have done during past dreams upon experiencing a dream sign, you're learning from your mistakes. You aren't learning from your mistakes by simply repeating a mantra and focusing on things unrelated to your past dreams during the day.

After every dream, you should recall it before writing down what dream signs you missed. Once you do this, for each dream sign, reimagine experiencing it only with you becoming lucid from it. Then tell yourself next time I experience [dream sign] I'll become lucid. That way, next time you experience a similar dream sign during a dream, you'll be more likely to become lucid from it because you will be learning from your mistakes.