“Really!” you may object. “What’s my risk of falling in the shower? One in a thousand?” My answer: Perhaps, but that’s not nearly good enough.
Life expectancy for a healthy American man of my age is about 90. (That’s not to be confused with American male life expectancy at birth, only about 78.) If I’m to achieve my statistical quota of 15 more years of life, that means about 15 times 365, or 5,475, more showers. But if I were so careless that my risk of slipping in the shower each time were as high as 1 in 1,000, I’d die or become crippled about five times before reaching my life expectancy. I have to reduce my risk of shower accidents to much, much less than 1 in 5,475.
Now, one way to mitigate this risk is to only shower once a month, whether I need it or not. (Need, by the way, seems to be a subjective judgement. It seems I'm quite content stretching the interval between showers out quite a ways--but my wife and children prefer I adhere to a much shorter cycle. Apparently they don't have my safety in mind. Humpfh)
A much smarter way to address the issue and reduce risk is to change the environment in which you shower. Modern surfaces with better slip resistance, nice grab bars, alcoves to keep things tidy, controls in easy reach. These and other things will make for a much reduced cumulative risk.
The same applies to other areas--small changes, reducing what seem like small risks, that over time have a high likelihood of happening and bringing about nasty consequences.