^Your words confuse me. I recognize outside aids as an extension of your body, be it a crop, whip, spurs, or any other aid. Since we're both on the same page there, when do you ever apply pressure to the horse's shoulder in the saddle? I am familiar with using a crop at different places /behind/ your leg, but never in front of.
If this is the case, it's never something I have heard of. I was allowed to use the crop on the shoulder when I was a more novice rider, probably for the reasons that OP is mentioning. Causing the reins to get messy, or maybe a balance issue. But as I progressed I was told by my trainers that that was never acceptable, and was just lazy. I'd like to hear your thoughts, SEA.
The sensitivity of the internet baffles me.