Comparison is common in parenting circles ('she walked at 11 months, when did yours?'). It rarely produces anything useful and frequently produces anxiety — about your child, about your parenting, about whether you're doing it right.
Why comparison fails
Developmental ranges are huge and normal. Walking, talking, reading at very different ages all fall in normal range. Comparison to specific children is statistically meaningless. Anxiety about being 'behind' rarely accelerates development; usually just stresses parents and sometimes children.
What to track instead
Your specific child's trajectory. Are they progressing in skills over time? That's the meaningful measure, not where they sit relative to a friend's child. Concerns that warrant professional input (developmental milestones missed by significant margins) are different from comparison anxiety.
Notice the comparison instinct. Most of the time, it tells you nothing useful about your child. Most of the time, it tells you something about your own anxiety — which deserves attention separately.