I find these reflections really interesting both in how they mostly align but in some ways differ from my approach to my marriage with my husband (8 years of an also very stable and happy marriage).

Your 50% of time together approach is so wildly different from how my husband and I function and structure our lives, which is like 99% together since we run a small company together and have mostly the same friends and hobbies so we are rarely apart except from the occasional errand. What I find so cool and interesting about this is that while I don't think spending a ton of time apart would work for us given our personalities and the way we really heavily rely on each other for so many things (to the point that my husband carries my ID and keys for me), it clearly is what works best for you and your wife and your unique lives and personalities. Both of our approaches differ from the default in opposite directions, and I imagine some people would call my marriage problematically co-dependent and yours concerningly separate, but clearly they work for us since they have lead to marriages that are happy and free of excessive stress or conflict.

The only point I probably actually disagree with is the assumption that traditional gender roles are what they are for a reason (and the implicit presumption that there is some innate reason men prefer to do home projects and women prefer to host, etc). I personally think that in many cases we end up falling into those traditional roles because of societal conditioning, not an innate preference or inclination. For example, I tend to worry more about the house being clean and tidy when we are hosting people, even though my husband is actually innately a more clean and tidy person than me, but I have it ingrained somewhere deep in my head that if our house doesn't look a certain way it will reflect badly on me in particular, whereas my husband doesn't have those same hangups. I'm defaulting to traditional gender roles out of obligation rather than desire, but I think it would be easy for my husband to assume that I am more naturally inclined to housekeeping chores if we didn't analyze it and actively work to align responsibilities' with our real preferences and not just what we've been conditioned to care about. We are both happier if I let my husband do the cleaning, which he actually enjoys, so I can have the time to maintain our yard, which I actually enjoy. At the end of the day, I agree with you that the most important part is for each couple to build the marriage that suits them as individuals whether they align or are opposed to traditional roles.

I also agree that being on the same team and having aligned principles are the biggest keys to a successful partnership. All the other stuff either falls into place on its own or can be easily adjusted with minimal effort as long as those two key things are in place.