I’ve Noticed Small Changes in the Figures for a Particular Date and Time - Why Is This?

The scores seen in the Apple Watch app are "live" scores and always relative to the current 60-day baseline we take from the Health database on iPhone. This means that even small changes in your 60-day baseline can have a minor impact on score calculations.

Overall the trend will be the same, but because your baseline can change, you may see these small variances.