From 100% full charge over a 32-day period, I used the Enduro in 18 combined Trail Run and Ride activities totalling 284km in 34:07:35 with 26% charge left enough to last another 33 days in watch mode or 19 hours of activity time. All activities in full GPS mode (Every Second Recording, GPS+GLONASS or GPS+GALILEO and Heart Rate). There’s more than enough battery life to handle more than a 100-miler event.
Stock functions removed or disabled include Activity Tracking, Pulse Oximeter, Widgets (ABC, Respiration, Stress, Body Battery, Hydration), Notifications, Bluetooth (turned on only for activity syncing), Watch face is stock Garmin.