I have recently been training to draw from concealment. In the summer this is a short sleeve, button up shirt that is untucked. I carry my Sig P365 OWB at around the 4 o’clock position.
To reach to my right, pull up my shirt, clear the holster, and fire with practical accuracy takes me at least 3 seconds. While doing dry fire training, in my haste I have dropped my pistol twice! I was in an indoor range with no A/C. I was sweating and the pistol just got away from me. Great training though, and a great thing to learn about hot weather weapon handling.
I continue to train, but getting a cover garment clear is not as easy as I once thought. Wearing a tee shirt with an unbuttoned shirt is way easier and I will adapt my wardrobe accordingly.
It is amazing what you learn while doing realistic training. The 21 foot rule for me, at least right now, would not allow me enough time to get off an aimed, effective shot.