A good sweet spot ride for me is 40 to 50 miles and 3,000 feet of climbing. I started regular cycling after a multi year break in January 2018 and maybe 15 miles and almost no hills was good for me. 2019 I started group rides and found 20 to 25 with some hills good as my new sweet spot. 2020 got me to 40 to 50 miles. This year I learned to enjoy hills with some others from the group. In 2020 and 2021 I averaged a little over 100 miles a week. I'm turning 61 in less than 2 weeks.