RA-4 is commercially used as a replenished system but with the small quantities I use running to exhaustion has proved more practical. (This is in contrast to C-41 where replenishing works great for me.)
To get the best capacity I have found that keeping the chemicals "clean" is the biggest issue. To that end I use the following process
I start by using the develop and blix times for appropriate for the temperature then after 4-6 sheets start bumping the time a bit. Mostly by mood.
I'm using a JOBO and normally about 160ml working solution, it is no longer a surprise when the 15th & 16th 8x10s come out just fine.