They would get used at minimum 3 times a week for at least 2 hours, and then the last two years they would get used 7 times a week for at least 1.5 hours.
The last year or so I had to charge them every three workouts, so the battery was lasting 4.5 - 5 hours or so. They would still quick charge though, so 15 minutes of charging would be enough for a long workout.
About a month ago they stopped charging, no matter what I tried. I ended up buying the Beats Flex and the Powerbeats Pro. The Flex at $70 is a steal, and so far lasts about 12 hours before needing recharging. I've been using them almost daily around the house.
The Powerbeats Pro I've been using when heading to the gym when lifting, the lack of cord around the back makes them a better choice.
Anyway, the Beats Flex are holding up well over the last month or so... but the original Beats X definitely held their own too over many years of service!