Hi Bill
You are correct: the topic of how much yin to do and when has been raised before. You can check
here and
here for a couple of examples. But, in general, there is no one answer that works for everybody. What you need to know is - what works for you? In general, the older we get the more yin-like we become (stiffer and less mobile) so the more we need yin-like yoga. But at a broader level, physical health has 3 orthogonal axis: strength, endurance and mobility. Personally, at 65, I use resistance training for strength (push-ups, handstands, weights), running sprints and climbing stairs for endurance, and yin yoga for maintaining my flexibility and and mobility. I cycle through these 3 intentions over 3 days. As we get older, we also need a bit more recovery time, so having one day a week of no workouts and do 6 days of the cycle I just described may work well.
For you, however, the question is really, what are your priorities? Are you lacking mobility and are not so worried about strength or endurance? If so, maybe more yin yoga would be appropriate. However, if you feeling your strength is lacking more than flexibility, then less yin and more yang may be more appropriate. You will have to decide your priorities and intentions and go from there to design your program?
Good luck!
Bernie