There is a new rule which most of us are not aware as it was incl during the last pay commission.
You can not avail LTC under 177B in the consecutive years even if the blocks are diff. eg: If you avail in 22 for block yr 21-22, then for block year 23-24 you can claim only in 24 and not in 23. Even I was not aware of this and learnt only after speaking to CDA