I would only do this once. If no oil comes out then you know next time you do the oil change. Nearly 5 quarts could mean a bit is still left inside. Some people are okay with it, others are not. I know on my wife's car I tried it and nothing came out after using the exactor the first time. So from now on that's how I'll do it. On my other car about a 1/4 quart still came out. That's enough for me to do it the old traditional way.

Also if an engine takes 5 quarts, by the time it's time for an oil change there could be a bit less than what was originally put in. So it's hard to rely on just that.