Whatever works for you, but I don't believe that your mail flow on the Mac is "effectively unchanged for 20 years".
Wikipedia lists many UI and functionality changes over the years for the Mail app.[1] As recently as this year, people are upset about changes in the Mail app in recent versions.[2]
Has the interface in Mail evolved since the early 2000s? Yes.
Does that constitute a material change, or even an adjustment, on my part? No.
Did I ever have to hack anything together to make this happen so smoothly for so long? Also no. ;)