I'm not sure where you read that, but it's not very good information. There are DVD players that will balk at discs that have very tightly packed PIF, whether in just one area or over the whole disc. But that does not make it a "bad" disc. As long as the max error level is within the standards, the disc is in spec.
You need to learn what levels and density your own players will tolerate, and go with that. Also keep in mind that the specs are for 1x scanning.