I had a few standard distance races last month (all 3 within 3 week time period). I compared my data after the first 2 as well to see where I could push it more. My max HR is about 175.
1 - Swim (152), Bike (152), Run (157)
2 - Swim (149), Bike (149), Run (152)
3 - Swim (155), Bike (154), Run (158)
I’d say 3rd race was my best performance, followed by 2 then 1 - so HR doesn’t paint the fully story in my case.