Mismatch in the Visits counts

Hi Team,

I am trying to work on one of the reports, where we are using a dimension, ALL VISIT segment against the metric Visits. Also im using few segments along with the all visit dimension. So when we combine all this segments it should be equal to the all visit dimension.
Example : ALL VISIT is a standard segment from Adobe. Segment 1 to segment 10 are different segments that have a count of certain visitors. when we sum up all these segments, it is greater that the all visit count.
NOTE: In all this 10 segments there are no duplicates.
So when i combine all this segments from 1 to 10 it should be equal to all visits, instead it is more than ALL VISITS. Can i know what could be the different scenarios of this visits mismatch.