True to an extent. Not to get totally off topic, but the CFM Valve Cover breather does take this into account. It has a check ball that closes off the VTA under vacuum. So, precisely when the PCV system is engaged (under vacuum) is when the breather is closed, allowing vapors to be sucked out. Then, when the crankcase is pressurized and the PCV valve closes, the check ball opens up to let the crankcase VTA.
Edit- are you talking about the oil cap replacement?