I always differentiate money for saving and money for investing, why? yes it is a form of my preparation so that I don't have to sell my investment when something urgent happens in the future because I still have savings money ready for me to use.
I definitely get the point of such a diversifying, however, I think, that this is also a matter of time. If you prepare your savings in fiat for a long time, they will become victim of inflation, unfortunately. This is why, in my opinion, from time to time you have to convert this fiat savings into more reliable assets. While having some savings in fiat, especially in cash, is undoubtedly important, it is also worth remembering that this form of keeping money is not truth worthy.
I totally understand what you mean about fiat savings. And I realized that, and I also used the money for my further additional investments, over a period of time.
I am usually flexible in terms of time, it could be once every 3 months or more than that I change my savings for additional money that I allocate for investment. I'm usually 50/50 on this, by that I mean half I use it to buy assets and the other half I don't touch it at all. For the total amount I am usually flexible regarding the opportunities I see on Bitcoin, it could be bigger like 70/30 or smaller than that.