I'm glad to hear that you stopped riding a half halt by pulling on one rein - as that is definitely not a half halt. A half halt is ridden through your seat and leg to encourage the horse to lower its haunches and rebalance - pulling on the reins is counter productive ;)
Basically, you can let your hands go forward, up and sideways, but never backwards. Any pulling back on the reins and you will be causing blockages and discomfort to your horse.
It didnt take long for my horse to tell me to stop pulling, and im glad he did it makes me a better rider. So i always try and listen to my horse because they have allot to teach me ! More than instructors sometimes.
The foolish reject what they see, not what they think,
The wise reject what they think, not what they see.