Don't Trust Connect Time in SMF Type 30 for FICON Environments

I received the following tip from Enterprise Performance Strategies. 

If you're using SMF Type 30 connect time to gauge I/O performance, be careful - in FICON environments, that number is essentially meaningless.
 
Per IBM's documentation on the SMF 30 record's IO_CONNECT_SEC field: "The value of RqsvAIC for the FICON® channel utilization cannot be calculated. In this case, the system adjusts the connect time for FICON DASD to be 1 millisecond per request." (source https://www.ibm.com/docs/en/z-logdata-analytics/5.1.0?topic=data-smf-30-v2-record-type)

Here's why that matters: connect time has historically represented actual data transfer time. But when FICON introduced concurrent active I/Os per channel, that measurement got too complicated to capture accurately - so the system just hard-codes it to a flat 1ms per request instead.
 
Years ago, when average I/O response times were around 3ms, that 1ms floor was a reasonable stand-in. Today, with response times often well under 1ms (some experts suggest 0.1–0.2ms is closer to reality) that artificial 1ms number is now larger than many actual total response times. It throws off any comparison against more granular records like Type 42 (datasets) or Type 101 (DB2).
 
Bottom line: Don't rely on Type 30 connect time in FICON environments to judge batch I/O performance - use Type 42, Type 101, or other record types that capture true connect time instead.