If memory serves me correctly, I think you can only take tax-free exclusion zone leave the first time you take leave after re-deployment.
Even if you did not consume all of your tax-free leave on your first leave period after re-deployment, the tax-free nature is forfeited for all subsequent leave.
For example, let's say you earn 20 days of tax-free leave. After re-deployment, you go on block leave for 10 days. That's tax-free. A couple of months later, you go on leave again for 10 days. That second period of leave doesn't count as tax-free leaves, and instead reverts to normal leave.
At least, this is how I recall the finance office explaining it to me. I haven't researched the statute.
This might account for the differences you saw among different people of the same rank.