I have put way too much thought into this myself.
But, I have a customized daily planner (binder with spreadsheets I designed for myself) with a LOT of life organization inside, including an energy management tool. I have taken data of my energy cycles over the course of a day, the week, a month, and a year. It's still ongoing, and it shifts as I learn more. I only plan life events according to when I predict that I will have energy for them. I have also learned that I can only handle 2 or 3 "special events"/schedule changes a week without getting completely drained or shutting down. If it is a highly social event, only once per week.
On maintaining friendships, I have another spreadsheet within the "community" section of my binder. Down the left side it lists all of my friends/family I need to maintain some level of contact with. Along the top, it lists the months and I simply check off when I've made contact. For most, once a year is sufficient and is an improvement. All of these friendships are over 10 years. I haven't made any new friends in a significant time and feel kind of full as it is.