It all depends on where you live. Here in Brighton the worst weather always comes from the SW which means windows can sometimes look like they not been done less than a day later. If the weather and rain comes from the north or east, it doesn't make much odds as the rain from those directions tends to be very clean rain.
If it's bucketing down, I'm no hero. I go home or not bother in the first place.
Thursday evenings I do quite a few shops, some shop signs, and some town centre 1st and 2nd floors simply because there's very few people around compared to the nightmare of during the day, parking, etc.
Today, Friday, after the strong winds blowing sea salt over them, they looked like they hadn't been done.
On Monday and Tuesday this week I did a pile of houses well away from the coast in the on/off drizzle and light rain. From experience I know those places aren't affected by anything other than the worst storms.
For me, working in the rain depends on the job, where it is and the type of job and there is no hard and fast rule.