i downloaded the "holiday jumper" christmas sweater looking one and noticed battery consumption was down big time. I am guessing because there are no seconds being displayed and additional data field is minimal (only one optional slot), also to note there is a screen loop mode which changes the display whenever you gesture, but I have only one screen set as permanent. Try the watch faces without seconds or other changing display features.
Have to give another plug for 'Rails'. Most energy efficient face I've seen, even more so than the default Garmin ones. Latest update has added weather functions, and some other HR metrics.
Am getting 0.25%/hr on F5x Plus with weather, Always-On seconds, etc
I also use Rails and SC8, both without relevant battery drain, but this can change with firmware updates of the watch. I had this effect on my Fenix 3 when suddenly a watchface drained the battery after an update of the watch.