That was my experience, immediately excellent results from the first haphazard placement. Tried a lot of things- moving subs (including the crawl method), reversing and adjusting phase, even tried different series/parallel to get 4, 8 and 16 ohms. Tremendous amount of work to learn almost all the difference is in setting crossover and level. Next would be impedance. Then springs. Moving the subs around, phase, etc, hardly noticeable at all.
You can mess with apps, a lot of guys just love tech, but I wouldn't waste my time. The problem is the equal loudness curves. The lower we go the more the volume levels converge. And these things go low! What this means is you can tweak and do whatever to get perfect results by whatever meter you use, and even get it to sound absolutely perfect. At one volume level. The minute you turn it down, there went the bass. Or turn it up, oh now too much. Its like you need a continuous loudness adjustment.
Also some recordings have near zero really low bass. If you adjust levels using one of those, good luck, a better recording will blow you out. Or just the opposite, some are real bass heavy. This is not like trying to get midrange/treble right because those are there all the time every recording you can hear them just fine. Deep bass however, until you get a DBA its hard to believe just how much deep bass has been there all along, its just been in hiding.
So what I did, after zinging back and forth pretty dramatically in the beginning (because of all the above reasons) was just let it alone a while. Listen to a lot of different stuff at a range of volume levels. Then every once in a while make a judicious teeny tiny little tweak. Lather rinse repeat. Takes a while but got to where its been pretty amazing for quite a while now.