I'm using 4th gen Fossil AW, no issue on battery. I dont think there's significant difference between most AW, they have similar SOC and relatively small battery. Fossil group owns many many watch brand ( or licensed to make watch for them ), so internally similar.
What I notice that got difference are mediatek SOC have better battery life, but can notice lower performance.

Well that's almost accurate, most AW only last 8-10 hours in real life. One day battery life is normal.