I hear a lot of people having issues with the Galaxy wearable app after an update draining the battery but I can't comment on this as I have a Galaxy watch and I don't have any problems with battery life. As a work around you could try doing a watch reset and turning off auto updates to the app and see how you get on. Also watch this video, his tips for saving battery work really well.
My issue isn't around trying to find fixes to save battery life. That's not why I bought the watch. I need it connected and useful all the time. Shutting down apps and features makes it 6 pointless having a smart watch. My issue is that the battery used to last a few days, now I get about 5 hours max and I've not changed my usage, apps or features. Why?