I have never been overly confident in my ability to adjust fan belt tension by "feel," so I recently bought belt tension gauges for both serpentine and conventional fan belts. I must say that I was shocked at the degree of tightness required to meet the service manual specifications. My "by feel" tensions were off by nearly 50% on the low side.
As far as I know, there have been no negative consequences associated with the low tension. (I had thought that a pulley failure on a Jeep Cherokee was possibly due to excessive tension, but evidently not.) I was just wondering if anyone else has any insight on the subject.