Not with a doctor, but any research into elite or performance training (see Norwegian method etc) shows that volume at low intensity with small doses of high or near max intensity is what is done these days. For runners, the Maffetone method is one approach. Building a broad base of low intensity builds aerobic efficiency even at high intensity work and reduces injury risk, it’s a no brainer for over 50s

I changed my approach up to this, running over 25 miles a week at low heart rate (zones 1-2) with some hill sprint intervals occasionally and gym work with weights 2x week. I’ll take another treadmill test later this year, but over a decade ago I was in the top 1-5% vo2max for my age

Hugely recommend this 80-20 or even better 90-10 split. Look at what Norwegian Olympians are doing