Depends. However string measurement on both of my horses ended up being very precise (even though some people didn't believe they make it that tall given a fact both were tiny when I got them as yearlings :) ).
13.1 (at 20 months) -> 14.3
13.2 (at 20 months) -> 15.1
"Life isn't about waiting for the storm to pass: it's about learning to dance in the rain..."
"When we are no longer able to change a situation - we are challenged to change ourselves."
"How people treat you is their karma; how you react is yours."