When I was 100% trad I didn't tend work in the rain. If it started raining while I was working, provided it wasn't too heavy, I used to carry on untill it all got too wet to continue. If it was raining before I started work then it was a day off.
I always felt uneasy about the way the ladder felt slippery in the rain. I was also never happy about the feet of the ladder on a wet surface even though the ladder had large articulated feet on it.
Plus, detailing around the edges of the window got more arkward as the microfibre got wetter from the rain.