I have been using copious amounts of RC paper, mainly Ilford MGIV Pearl; I find that there is a very slight dry down effect.
The way the print is dried also has an effect, slight, but still there.
I have a heated RC paper, roller dryer, which means I have a wet to dry 8x10 print in about 34 seconds. Prints dried this way seem to retain their luminosity better, I cannot explain it any other way.
When I hang wet prints up to dry and then compare an air dried print with a Roller heater dried print, the force dried print wins out by a poofteenth. The force dried prints seem to have a slight sparkle, that is only available in an air dried print by pulling exposure by 1/12 of a stop.
In my own darkroom with my current MGIV RC paper stock, I know I need to pull a wet print by 1/16 of a stop if it is going to be air dried.
When doing large batch printing, which can be anything from 20 to 500 or more prints off the same neg, I keep a print under water in a dish, so I can do a quick running check after another load of prints have hit the fixer.
I quickly pull the reference print out with my left hand and pull one of the latest prints out with tongs, then check them side by side.
Mick.