Oh I was just borrowing your words for "longevity framework" aha. I've taken a look at your website, and it seems like you have a much more well-defined "framework" than I do, given your commitment to a healthy diet, regular physical exercise, etc. In fact, I wouldn't say I have a longevity framework at all. It's an interesting concept though, and I feel like I certainly could learn from you by establishing a more formal set of health-guidelines for myself, so thanks for the idea!
I was first exposed to the idea of cold showers for better health in Veritasium's "How to Slow Aging (and even reverse it)" https://www.youtube.com/watch?v=QRt7LjqJ45k. The video isn't focused on cold showers exclusively, but he briefly touches upon it as a method of improving longevity. I figured that implementing cold showers into my daily routine should be a pretty easy task, because it doesn't add any extra work into my schedule--it's just replacing a small portion of my hot showers, which I should be minimizing anyway.
And yeah, you're probably right about cold showers being less of a good idea in the evening. How often do you shower then? I can't bring myself to go to bed at night without feeling clean, but showering twice in a day also feels a bit time-consuming and excessive.