I sometimes practice without warmup strokes - it does a couple of things for me:
- forces me to pay closer attention to my PSR and setup
- forces me to focus and aim more quickly
pj
chgo
IIRC, Mark Wilson was an advocate for this as a practice technique. I have done it for years and it does test one's PSR/alignment consistency. But, it does not feel natural for me to play that way; I use it as practice only.