Hi Diego - I had issues like this when I first set up ST a few months back. My wife had no issues with her iphone 6, but my GS6 was a nightmare. I was at work and I would randomly be seen as arriving at my house. I’m not quite sure what was causing that (other than my phone doesn’t get good GPS signal in my office).
I ended up switching to life360 as a presence sensor. It has an integrated app that ties into smartthings. I also downloaded an app called GPS Status that keeps gps in the background. It drains my battery about 10-15% faster than usual, but the combination has been way better for me.
I would also suggest that you create an exception to your lock/unlock automation to not fire when you guys are home sleeping. I have a night mode set up as an exception to mine and it allows me to sleep much better at night