*this* - really no substiture for play testing. I'll use a level to get it in the ballpark, but then dropping a ball from the center of the playfield repeatedly, watching for SDTM (straight down the middle) accuracy between the flippers. Play a few games and see how the shots feel. Games like Taxi and Pinbot with vortex skill shots can be affected by the leveling as well. I find that dialing it in for a good feel of play sometimes means ignoring what your level tool tells you.

Well, I do use the right tools at first. It's just that when I start playing, I'll often end up tweaking in the level for one reason or another. I know a lot of folks will just live by what the tool says and leave it at that. Sometimes it just feels like a game is not quite right when the ball rattles around at the in/outlane area, maybe it feels like it tends to be draining a lot to the on one side. I might revisit the leg levelers a few times before I am satisfied in the feel, the randomness of bouncing, the shot capability, the speed, etc...

I'm not the only one...

"Using a level gets it close to true, a ball test finishes the job.
I've always trained my staff to test the playfield by rolling a ball
down the center several times. If it rolls true then the playfield is
level."

"The ball is the true indicator of a true playfield"

"I always level by feel alone...play, adjust, play, play, adjust, play"