I know this a northern hemisphere thread but for interest this how it works in Australia.
We have RV (runway visibility) which is by observation and RVR which is instrumented only. Our transmissometers are approved for fog and mist only. We don't use the term IRVR. Melbourne was the first and currently the only CAT III installation, Sydney has CAT11.
Knowing the approach ban and 1000 ft requirements, we asked the airlines what they wanted in the way of RVR reports. The answer was they wanted an RVR check on first contact with the tower and nothing after that. Rather than initiate a MAP due to a subsequent report, they prefer to get the first contact report and fly down to the decision height. On departure, an RVR report is passed after the aircraft reports ready, before crossing the holding point.