Your company have all the details of the Flow restrictions and the reasons why. They are all published to the airlines for every Flow restriction. Ask them. If the restriction and the reality are different get them to ask for an explanation.
Some airline Ops depts are too lazy to learn to understand the messages that are sent to them and the pilots are told cock and bull stories about delays ... which probably explains why we all hear it repeated in PA addresses.
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Go with the flow ... or you'll miss your slot.