In the parameter definition :
“To allow the best throughput in DL, it is strongly recommended to set this parameter to 0 (DISABLE) i.e. to not forbid the resegmentation.”
When you enable this parameter, you actually force the system to stay in high MCS.
When you disable it, you actually allow it to use lower MCS.
In both caases, the IR is used whenever possible !
In case of network with good radio conditions all over, you can try to set it to “ENABLE”. But in typical networks, with sometimes bad conditions, it is safer to keep it at “DISABLE”.
(sorry for the late reply)