From a natural anecdotal experience, I wouldn’t say a very strict optimized diet is necessary for the every day person. I do advocate for blood work, more specifically to monitor blood sugar and cholesterol, and adjust diets accordingly. Keep an eye on blood pressure, and family history. Diabetes and heart diseases is a serious and common issue in the modern day world, and majority of it comes down to over consumption, lack of exercise, and consuming way too much sugar (soda).
When it comes to working out, I was on a calorie deficit to cut fat quickly, but I eventually hit a point where I could not maintain my energy through the day, workouts were harder to recover from. Increasing my calories, increased my energy, reps, and recovery time. Again may be anecdotal, but it seems a lot of the research reflects my experiences, so I’m rolling with it.